Validate foreign key `fk_rails_494e57ee78_p`

This foreign key was added in !166318 (diffs) to replace the corrupted ones from #487947 (comment 2101608662) and when the cleanup of orphaned rows is complete we can validate it.

Process:

• Use prepare_partitioned_async_foreign_key_validation to validate the FK over the weekend: https://docs.gitlab.com/ee/development/database/add_foreign_key_to_existing_column.html#validate-the-foreign-key-asynchronously
• When the FK is valid on .com, use add_concurrent_partitioned_foreign_key to add the FK between the routing tables. Same call as the one from the original MR, but with the validate: option set to true.

Details:

  SOURCE_TABLE_NAME = :p_ci_builds
  TARGET_TABLE_NAME = :p_ci_pipelines
  COLUMN = :auto_canceled_by_id
  TARGET_COLUMN = :id
  PARTITION_COLUMN = :auto_canceled_by_partition_id
  PARTITION_TARGET_COLUMN = :partition_id
  FK_NAME = :fk_rails_494e57ee78_p