Finish CI FKs conversion and create new partitions

What does this MR do and why?

!126122 (merged) failed to get the locks on ci_builds and p_ci_builds_metadata to complete the FK conversion. I think we have a better chance of getting the necessary locks during the weekend, since we have lower traffic.

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Before	After

How to set up and validate locally

marius@rocket-sled ~/W/g/gitlab (414396-complete-ci-builds-partitioning)> GITLAB_SIMULATE_SAAS=1 pgai use -o ci bin/rails runner "Feature.enable(:complete_p_ci_builds_partitioning); Gitlab::Database::CiBuildsPartitioning.new(logger: Gitlab::JsonLogger.new(STDOUT)).execute"
{"severity":"INFO","time":"2023-07-17T12:20:33.939Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Lock timeout is set","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:35.141Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Migration finished","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:35.507Z","message":"Foreign key successfully renamed","class":"Gitlab::Database::CiBuildsPartitioning"}
{"severity":"INFO","time":"2023-07-17T12:20:36.038Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Lock timeout is set","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:36.780Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Migration finished","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:37.142Z","message":"Partition for p_ci_builds successfully created","class":"Gitlab::Database::CiBuildsPartitioning"}
{"severity":"INFO","time":"2023-07-17T12:20:37.672Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Lock timeout is set","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:37.874Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Migration finished","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:38.234Z","message":"Partition for p_ci_job_annotations successfully created","class":"Gitlab::Database::CiBuildsPartitioning"}
{"severity":"INFO","time":"2023-07-17T12:20:38.768Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Lock timeout is set","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:38.969Z","method":"with_lock_retries","class":"Gitlab::Database::CiBuildsPartitioning","message":"Migration finished","current_iteration":1,"lock_timeout_in_ms":10000}
{"severity":"INFO","time":"2023-07-17T12:20:39.326Z","message":"Partition for p_ci_runner_machine_builds successfully created","class":"Gitlab::Database::CiBuildsPartitioning"}

Subsequent executions are skipped:

marius@rocket-sled ~/W/g/gitlab (414396-complete-ci-builds-partitioning)> GITLAB_SIMULATE_SAAS=1 pgai use -o ci bin/rails runner "Feature.enable(:complete_p_ci_builds_partitioning); Gitlab::Database::CiBuildsPartitioning.new(logger: Gitlab::JsonLogger.new(STDOUT)).execute"
{"severity":"INFO","time":"2023-07-17T12:21:32.625Z","message":"Foreign key already renamed, nothing to do","class":"Gitlab::Database::CiBuildsPartitioning"}
{"severity":"INFO","time":"2023-07-17T12:21:32.801Z","message":"p_ci_builds partition exists, nothing to do","class":"Gitlab::Database::CiBuildsPartitioning"}
{"severity":"INFO","time":"2023-07-17T12:21:32.977Z","message":"p_ci_job_annotations partition exists, nothing to do","class":"Gitlab::Database::CiBuildsPartitioning"}
{"severity":"INFO","time":"2023-07-17T12:21:33.153Z","message":"p_ci_runner_machine_builds partition exists, nothing to do","class":"Gitlab::Database::CiBuildsPartitioning"}

MR acceptance checklist

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Related to #414396 (closed)