Project push rules: Migrate project push rules to dedicated table

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Implementation plan

We want to use the push_rules table as a dedicated table for projects. Therefore, we should remove push_rules records belonging to a group or organization.

• Create a migration to destroy push_rules records where organization_id is populated.
• Create a migration to destroy push_rules records associated with a group (where push_rule_id is not null).

Expectations

• Follow this guideline for data migrations https://docs.gitlab.com/development/database_review/#preparation-when-adding-data-migrations
• Cover the migrations result with specs.
• Collaborate with the database team to get a review.

Next Steps

• Create a new table migration project_push_rules (w1)
• Add triggers to copy data from push_rules to project_push_rules similar to what we have for organization_push_rules and group_push_rules (w2)
• Write a BBM to copy historical data from push_rules to project_push_rules (w2)
  • Account for duplicates logic in BBM: !199307 (closed)
  • migrate missing records: !219705 (merged) (18.9)

Implementation Plan

Step	Milestone	Weight	Done?
Create project_push_rules table	18.6		✅ Done
Sync project_push_rules on push_rules write operations	18.6		✅ Done
BBM to copy push_rules data to project_push_rules	18.7	2	✅ Done
Migrate duplicate push_rules to project_push_rules	18.7		✅ Done
BackfillMissingProjectPushRules migration	18.9	2	✅ Done
Reset project_push_rules id sequence to prevent UniqueViolation errors	18.10	2	MR ✅ Done
Write switch code (FF off)	18.10	3	Implementation plan
Enable FF on GitLab.com	18.10	1
Finalize BBM	18.11 (a required stop)	1
Enable FF for self-managed	19.0	1
Cleanup the read_project_push_rules, and write_project_push_rules feature flags	19.1	1
Remove unused project_settings.push_rule_id column	19.1	2
Remove project push rules sync triggers after table migration	19.1	1
Move push rule models under PushRules:: namespace	19.1	2
Drop the push_rules table	19.2	1