Backfill default_branch_protection_defaults for namespace settings

What does this MR do and why?

Backfill default_branch_protection_defaults for namespace settings

This commit backfills default_branch_protection_defaults for namespace settings table

Changelog: other

Query Logs

Read Query https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/23716/commands/76137

Write Query https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/23716/commands/76140

Migration Logs

rails db:migrate
main: == [advisory_lock_connection] object_id: 180860, pg_backend_pid: 85619
main: == 20231107092912 QueueBackfillBranchProtectionNamespaceSetting: migrating ====
main: == 20231107092912 QueueBackfillBranchProtectionNamespaceSetting: migrated (0.0613s)

main: == [advisory_lock_connection] object_id: 180860, pg_backend_pid: 85619


❯ bundle exec rake db:rollback:main STEP=1
main: == [advisory_lock_connection] object_id: 181400, pg_backend_pid: 84882
main: == 20231107092912 QueueBackfillBranchProtectionNamespaceSetting: reverting ====
main: == 20231107092912 QueueBackfillBranchProtectionNamespaceSetting: reverted (0.0400s)

main: == [advisory_lock_connection] object_id: 181400, pg_backend_pid: 84882

How to set up and validate locally

1. Run rails console.
2. Enter NamespaceSetting.update_all(default_branch_protection_defaults: {})
3. rails db:migrate
4. Check NamespaceSetting's default_branch_protection_defaults column is correctly filled.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #408152 (closed)