This PR handles the situation where a structured property is deleted when it's referenced on a form, we will remove the prompt from the form. Do this by updating the delete entity service to look for a prompt deletion and find the forms with this prompt on it, then removing that prompt.

In order to find the forms with this prompt on it, we needed a new @Searchable on the structured property urn on the form prompt. In order to make this work for existing forms, I added a new upgrade step to update the elastic index for forms with these prompts.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub