resolves #722, resolves #720, resolves #712

This is a:

• documentation update
• bug fix with no breaking changes
• new functionality
• a breaking change

All pull requests from community contributors should target the main branch (default).

Description & motivation

Fixes the issue where cross-db deprecation warnings are shown during project parsing, which means they come up even in macros which have migrated to the new code

Checklist

• This code is associated with an Issue which has been triaged and accepted for development.
• I have verified that these changes work locally on the following warehouses (Note: it's okay if you do not have access to all warehouses, this helps us understand what has been covered)
  • BigQuery
  • Postgres
  • Redshift
  • Snowflake
• I have added an entry to CHANGELOG.md