Add partial index on oauth_access_grants for cleanup worker

What does this MR do and why?

Add partial index on oauth_access_grants for cleanup worker

Adds partial index on (id) WHERE revoked_at IS NOT NULL to optimize the upcoming OauthAccessGrantArchiveWorker.

Relates: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/377995
Changelog: performance

References

Main: #377995 (closed)
Worker: !207837 (merged)

Details

Table size: 43 GB (bloated - actual data ~6 GB)
Estimated storage cost: ~42 MB

Database

Migration

>>> Executing: bin/rails db:migrate:up:main VERSION=20251007154446
main: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 67734
main: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: migrating ========
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0164s
main: -- index_exists?(:oauth_access_grants, [:id], {:where=>"revoked_at IS NOT NULL", :name=>"index_oauth_access_grants_on_id_where_revoked", :algorithm=>:concurrently})
main:    -> 0.0035s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0003s
main: -- add_index(:oauth_access_grants, [:id], {:where=>"revoked_at IS NOT NULL", :name=>"index_oauth_access_grants_on_id_where_revoked", :algorithm=>:concurrently})
main:    -> 0.0166s
main: -- execute("RESET statement_timeout")
main:    -> 0.0004s
main: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: migrated (0.0721s) 

main: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 67734
>>> Executing: bin/rails db:migrate:up:ci VERSION=20251007154446
ci: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 67786
ci: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: migrating ========
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- view_exists?(:postgres_partitions)
ci:    -> 0.0134s
ci: -- index_exists?(:oauth_access_grants, [:id], {:where=>"revoked_at IS NOT NULL", :name=>"index_oauth_access_grants_on_id_where_revoked", :algorithm=>:concurrently})
ci:    -> 0.0059s
ci: -- execute("SET statement_timeout TO 0")
ci:    -> 0.0003s
ci: -- add_index(:oauth_access_grants, [:id], {:where=>"revoked_at IS NOT NULL", :name=>"index_oauth_access_grants_on_id_where_revoked", :algorithm=>:concurrently})
ci:    -> 0.0052s
ci: -- execute("RESET statement_timeout")
ci:    -> 0.0003s
ci: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: migrated (0.0674s) 

ci: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 67786

Rollback

>>> Executing: bin/rails db:migrate:down:main VERSION=20251007154446
main: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 70614
main: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: reverting ========
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0181s
main: -- indexes(:oauth_access_grants)
main:    -> 0.0023s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0003s
main: -- remove_index(:oauth_access_grants, {:algorithm=>:concurrently, :name=>"index_oauth_access_grants_on_id_where_revoked"})
main:    -> 0.0022s
main: -- execute("RESET statement_timeout")
main:    -> 0.0003s
main: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: reverted (0.0598s) 

main: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 70614
>>> Executing: bin/rails db:migrate:down:ci VERSION=20251007154446
ci: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 70696
ci: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: reverting ========
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- view_exists?(:postgres_partitions)
ci:    -> 0.0183s
ci: -- indexes(:oauth_access_grants)
ci:    -> 0.0059s
ci: -- execute("SET statement_timeout TO 0")
ci:    -> 0.0004s
ci: -- remove_index(:oauth_access_grants, {:algorithm=>:concurrently, :name=>"index_oauth_access_grants_on_id_where_revoked"})
ci:    -> 0.0031s
ci: -- execute("RESET statement_timeout")
ci:    -> 0.0004s
ci: == 20251007154446 AddIndexToOauthAccessGrantsIdWhereRevoked: reverted (0.0786s) 

ci: == [advisory_lock_connection] object_id: 129160, pg_backend_pid: 70696

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