Add composite index on oauth_access_grants for cleanup worker

What does this MR do and why?

Add composite index on oauth_access_grants for cleanup worker

Adds index on (created_at, expires_in) to optimize the OAuth access grants cleanup worker performance when identifying expired grants.

Relates: #377995 (closed)

References

Database

Migration

daniele@dbracciani--20250523-VYV2F gitlab % bin/rails db:migrate                                                
main: == [advisory_lock_connection] object_id: 138920, pg_backend_pid: 64651
main: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: migrating ===
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0119s
main: -- index_exists?(:oauth_access_grants, [:created_at, :expires_in], {:name=>"index_oauth_access_grants_on_created_at_expires_in", :algorithm=>:concurrently})
main:    -> 0.0019s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0003s
main: -- add_index(:oauth_access_grants, [:created_at, :expires_in], {:name=>"index_oauth_access_grants_on_created_at_expires_in", :algorithm=>:concurrently})
main:    -> 0.0018s
main: -- execute("RESET statement_timeout")
main:    -> 0.0002s
main: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: migrated (0.0290s) 

main: == [advisory_lock_connection] object_id: 138920, pg_backend_pid: 64651
ci: == [advisory_lock_connection] object_id: 138920, pg_backend_pid: 64652
ci: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: migrating ===
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- view_exists?(:postgres_partitions)
ci:    -> 0.0003s
ci: -- index_exists?(:oauth_access_grants, [:created_at, :expires_in], {:name=>"index_oauth_access_grants_on_created_at_expires_in", :algorithm=>:concurrently})
ci:    -> 0.0034s
ci: -- execute("SET statement_timeout TO 0")
ci:    -> 0.0003s
ci: -- add_index(:oauth_access_grants, [:created_at, :expires_in], {:name=>"index_oauth_access_grants_on_created_at_expires_in", :algorithm=>:concurrently})
ci:    -> 0.0022s
ci: -- execute("RESET statement_timeout")
ci:    -> 0.0003s
ci: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: migrated (0.0175s) 

ci: == [advisory_lock_connection] object_id: 138920, pg_backend_pid: 64652

Rollback

daniele@dbracciani--20250523-VYV2F gitlab % VERSION=20250702142323 bin/rails db:migrate:down:main
main: == [advisory_lock_connection] object_id: 138620, pg_backend_pid: 65416
main: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: reverting ===
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0117s
main: -- indexes(:oauth_access_grants)
main:    -> 0.0062s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0003s
main: -- remove_index(:oauth_access_grants, {:algorithm=>:concurrently, :name=>"index_oauth_access_grants_on_created_at_expires_in"})
main:    -> 0.0018s
main: -- execute("RESET statement_timeout")
main:    -> 0.0004s
main: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: reverted (0.0480s) 

main: == [advisory_lock_connection] object_id: 138620, pg_backend_pid: 65416
daniele@dbracciani--20250523-VYV2F gitlab % VERSION=20250702142323 bin/rails db:migrate:down:ci  
ci: == [advisory_lock_connection] object_id: 138620, pg_backend_pid: 65465
ci: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: reverting ===
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- view_exists?(:postgres_partitions)
ci:    -> 0.0100s
ci: -- indexes(:oauth_access_grants)
ci:    -> 0.0026s
ci: -- execute("SET statement_timeout TO 0")
ci:    -> 0.0003s
ci: -- remove_index(:oauth_access_grants, {:algorithm=>:concurrently, :name=>"index_oauth_access_grants_on_created_at_expires_in"})
ci:    -> 0.0014s
ci: -- execute("RESET statement_timeout")
ci:    -> 0.0003s
ci: == 20250702142323 AddIndexToOauthAccessGrantOnCreatedAtExpiresIn: reverted (0.0293s) 

ci: == [advisory_lock_connection] object_id: 138620, pg_backend_pid: 65465

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