Clean up after incident 8204 (2023-01-05)

During gitlab-com/gl-infra/production#8204 (closed) we created records with mixed partition ids that will need to be fixed for the partitioning work to resume:

gitlabhq_dblab=# select count(*) from p_ci_builds_metadata where partition_id = 101;
 count
--------
 188112
(1 row)

gitlabhq_dblab=# select count(*) from p_ci_builds_metadata inner join ci_builds on ci_builds.id = p_ci_builds_metadata.build_id where p_ci_builds_metadata.partition_id = 101 and ci_builds.partition_id <> 101;
 count
-------
 82282
(1 row)

Because of this mismatch we won't be able to update the foreign key between p_ci_builds_metadata and ci_builds to use partition_id. This is likely happening for all 17 tables, but we need to add indexes on partition_id to know more.

Proposal

Add temporary indexes to the following tables and write migrations to update partition_id to 100

table name	temporary index created	merge requests for indexes	cleanup MR	cleanup completed
ci_build_needs	✅	!108823 (merged)	!111440 (closed)	✅
ci_build_pending_states	Not needed, will be updated by FK constraint on ci_builds			✅
ci_build_report_results	✅	!108823 (merged)	!111548 (merged)	✅
ci_build_trace_chunks	Not needed, will be updated by FK constraint on ci_builds		Not needed	✅
ci_build_trace_metadata	✅	!109084 (merged)	!111549 (merged)	✅
ci_builds	✅	!109085 (merged)	!111287 (merged)	✅
ci_job_artifacts	✅	!109084 (merged)	!111436 (merged)	✅
ci_job_variables	✅	!109084 (merged)	!111173 (merged)	✅
ci_pipeline_variables	✅	!108823 (merged)	!111420 (merged)	✅
ci_pipelines	✅	!109085 (merged)	!109981 (merged)	✅
ci_sources_pipelines	✅	!109094 (merged)	!109364 (merged)	✅
ci_stages	✅	!109085 (merged)	!111439 (merged)	✅
ci_unit_test_failures	Not needed, will be updated by FK constraint on ci_builds		Not needed	✅
p_ci_builds_metadata	Not needed, already covered by the partitioning constraint	covered by the partitioning constraint	!111576 (merged)	✅
ci_running_builds	✅	!108788 (merged)	Not needed	✅
ci_pending_builds	✅	!108788 (merged)	Not needed	✅
ci_builds_runner_session	✅	!108788 (merged)	Not needed, with !109316 (merged) it can be cascaded from ci_builds	✅