Reverts #13499

The Regional Access Boundaries PR to main. Contains all the changes
merged to the feature branch rebased on top of main.

P.S. Opening the PR directly to main as feature branch
regional-access-boundaries has drifted from main and opening a
rebased-PR to the feature branch shows 5k+ lines of code diff.

Reverts #13499

🤖 I have created a release *beep* *boop*
---


<details><summary>1.88.0</summary>

##
[1.88.0](v1.87.1...v1.88.0)
(2026-07-06)


### Features

* **auth:** Add support for Regional Access Boundaries
([#13499](#13499))
([b721e43](b721e43))
* automate libraries-bom tag and release creation on release publish
([#13655](#13655))
([7a7e2ff](7a7e2ff))
* **bigquery-jdbc:** add `EnableProjectDiscovery` connection property
for metadata methods
([#13344](#13344))
([ab9669a](ab9669a))
* **bigquery-jdbc:** migrate statement execution thread tracking to
connection-scoped executor
([#13454](#13454))
([341e51a](341e51a))
* **bigquery-jdbc:** respect standard JVM trustStore properties by
default
([#13435](#13435))
([7af3224](7af3224))
* **bigquery-jdbc:** support connection-scoped executor isolation and
dynamic queue warnings
([#13413](#13413))
([79e26b8](79e26b8))
* **bigquery:** add internal listProjects API to core client
([#13429](#13429))
([3580407](3580407))
* **bigtable:** route point read rows to shim
([#13542](#13542))
([2c7e5f5](2c7e5f5))
* **deps:** add jspecify to shared dependencies
([#13412](#13412))
([582053d](582053d))
* enable self-signed JWTs by default in ServiceOptions
([#13338](#13338))
([110d2b7](110d2b7))
* **gapic-generator:** Add NullMarked annotation to generated classes
([#13517](#13517))
([825dadd](825dadd))
* **google/cloud/agentregistry/v1:** onboard a new library
([#13509](#13509))
([6728816](6728816))
* scale up connection worker pool based on latency
([#13384](#13384))
([eb379b3](eb379b3))
* **spanner:** add settings for gRCP keep-alive
([#13643](#13643))
([9d78307](9d78307))
* **spanner:** auth login support for Spanner Omni endpoints
([#13470](#13470))
([55930b4](55930b4))
* **storage:** add checksum validation in the json read channel
([#13270](#13270))
([872d7b7](872d7b7))
* **storage:** add checksum validation on json read paths
([#13269](#13269))
([396b042](396b042))
* **storage:** add full object checksum validation for bidi flow
([#13266](#13266))
([9113d80](9113d80))
* **storage:** add full object checksum validation for grpc flow
([#13265](#13265))
([a5ba606](a5ba606))
* **storage:** Adding CumulativeHasher wrapper class for Full object …
([#13239](#13239))
([bd40324](bd40324))
* **storage:** adding disabling option for bidi reads
([#13506](#13506))
([591cae0](591cae0))
* **storage:** log additional bytes received from GCS in read path
([#13427](#13427))
([9492aa2](9492aa2))
* **storage:** update compose sample to support deleteSourceObjects
option
([#13493](#13493))
([50a8658](50a8658))
* use self-signed JWTs in Spanner MutableCredentials
([#13381](#13381))
([29543a2](29543a2))


### Bug Fixes

* Add logging-logback to gapic-libraries-bom
([#13663](#13663))
([512e370](512e370))
* **auth:** Fix UserCredentials serialization clientSecret leak
([#13465](#13465))
([2d9d01c](2d9d01c))
* **auth:** handle missing APPDATA on Windows gracefully
([#13471](#13471))
([77e84a9](77e84a9)),
closes
[#12565](#12565)
* **bigquery-jdbc:** add proper version to BigQueryDriver
([#13294](#13294))
([9fd84fc](9fd84fc))
* **bigquery-jdbc:** avoid rollback on statement close in manual commit
mode
([#13503](#13503))
([79bbee1](79bbee1))
* **bigquery-jdbc:** correct `FilterTablesOnDefaultDataset` fallback
logic
([#13625](#13625))
([f7eb23d](f7eb23d))
* **bigquery-jdbc:** ensure largeResults are handled in
PreparedStatement
([#13496](#13496))
([d3e7a19](d3e7a19))
* **bigquery-jdbc:** ensure test uses unique dataset & cleans up
([#13587](#13587))
([a6bb362](a6bb362))
* **bigquery-jdbc:** explicitly set location when available for
temporary dataset
([#13508](#13508))
([40cd0a7](40cd0a7))
* **bigquery-jdbc:** propagate connection proxy settings to auth library
([#13539](#13539))
([87dda5d](87dda5d))
* **bigquery-jdbc:** shade org.slf4j
([#13547](#13547))
([7ef1312](7ef1312))
* **bigquery-jdbc:** update format validation tests to create tables for
the test
([#13588](#13588))
([4bb3a61](4bb3a61))
* **bigquery-jdbc:** update Maven Central artifact link in the README
([#13563](#13563))
([8707a65](8707a65))
* **bigquery:** retry cancel job and routine creation on transient HTTP
5xx errors
([#13416](#13416))
([35eb041](35eb041))
* **bigquery:** route JOB_CREATION_REQUIRED through fast query path
([#13437](#13437))
([64cde7f](64cde7f))
* **bigquery:** Update fast query path to allow jobTimeoutMs in the
request
([#13502](#13502))
([1a6f4d5](1a6f4d5))
* **bigtable:** honour session_load override when server-returned
session_load is 0
([#13629](#13629))
([b56f9b8](b56f9b8))
* **bqjdbc:** pass rowsInPage with TableResult
([#13238](#13238))
([203a91e](203a91e))
* **ci:** build dependencies before convergence check
([#13638](#13638))
([9de3209](9de3209))
* **ci:** ignore SNAPSHOT suffix in flatten-plugin check
([#13639](#13639))
([bb65627](bb65627))
* **ci:** run root install in dependency convergence check
([#13666](#13666))
([86d35e4](86d35e4))
* **ci:** skip existing-versions-check for gapic-generator-java-root
([#13590](#13590))
([a1f3b8a](a1f3b8a))
* **datastore:** Configure TraceExporter with Datastore credentials in
E2E tests
([#13627](#13627))
([d281a62](d281a62))
* **datastore:** disable built-in OpenTelemetry SDK when metrics export
is disabled
([#13543](#13543))
([53b7142](53b7142))
* **datastore:** reduce flakiness of E2E tracing tests
([#13645](#13645))
([8afc0ab](8afc0ab))
* **deps:** update dependency
com.google.apis:google-api-services-bigquery to v2-rev20260612-2.0.0
([#13570](#13570))
([ca5ff79](ca5ff79))
* **deps:** update dependency com.google.apis:google-api-services-dns to
v1-rev20260616-2.0.0
([#12796](#12796))
([0dd60ca](0dd60ca))
* **deps:** update dependency com.google.cloud:google-cloud-pubsub-bom
to v1.151.0
([#12097](#12097))
([d169006](d169006))
* **deps:** update dependency com.google.cloud:libraries-bom to v26.84.0
([#12663](#12663))
([95c7774](95c7774))
* **deps:** update first-party storage dependencies to
v1-rev20260524-2.0.0
([#13406](#13406))
([bdeedb8](bdeedb8))
* exclude java-vertexai from existing versions check
([#13632](#13632))
([edaa4e3](edaa4e3))
* fallback on VPC
([#13567](#13567))
([e8c428d](e8c428d))
* **java-cloud-bom:** execute pre-install pass in GHA release notes
generator
([#13608](#13608))
([c365c10](c365c10))
* **release:** check remote tags using git ls-remote to prevent already
exists error
([#13574](#13574))
([6cf0567](6cf0567))
* **spanner:** fail fast when inline-begin DML returns no transaction id
([#13536](#13536))
([94315ce](94315ce))
* **spanner:** pin inline read-write transactions to default endpoint
([#13562](#13562))
([6908dee](6908dee))
* **spanner:** remove explicit tink version to resolve dependency
convergence conflict
([#13602](#13602))
([863c26e](863c26e))
* **spanner:** update dynamic channel pool default configuration
([#13646](#13646))
([37b77c3](37b77c3))


### Dependencies

* Add org.bouncycastle:bcprov-jdk18on to java-shared-dependencies
([#13531](#13531))
([e3d2082](e3d2082))
* **auth:** Update commons-codec to v1.18.0
([#13598](#13598))
([fd89957](fd89957))
* Update gapic-showcase to v0.41.0
([#13582](#13582))
([09faaac](09faaac))
* Upgrade google-http-client to v2.1.1
([#13578](#13578))
([6abef19](6abef19))


### Documentation

* add instructions for manual code generation checks in CI
([#13596](#13596))
([f6162e2](f6162e2))
</details>

---
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Please](https://github.com/googleapis/release-please). See
[documentation](https://github.com/googleapis/release-please#release-please).

---------

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>