Project push rules: Remove organization and group records

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Collaborate/take over this issue

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.