The background migration MigrateMergeRequestDiffCommitUsers was wrapping
its updates in a transaction. This was a left-over from an early draft
of the merge request. As the bulk updates can take some time to
complete, this can lead to long transaction timings. On production this
ultimately lead to the incident described in issue
https://gitlab.com/gitlab-com/gl-infra/production/-/issues/5119, though
fortunately this didn't seem to negatively affect users.

This commit removes the transaction, and adds a migration to reschedule
all the background jobs (which have been removed from the queue).
Rescheduling all jobs is the simplest solution to ensuring all data is
migrated. Rows that have already been migrated will be updated again,
but that's not a problem. Any existing data in
merge_request_diff_commit_users will just be reused.

See the following for more details:

- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/63669#note_621297454
- https://gitlab.com/gitlab-com/gl-infra/production/-/issues/5119
- https://gitlab.com/gitlab-org/gitlab/-/issues/331823

Changelog: fixed

Update tests to simplify default branch migration

See merge request gitlab-org/gitlab!65556

Add service for uploading files in the Content Editor

See merge request gitlab-org/gitlab!65684

Updates description for `name` argument in CiTemplate Resolver

See merge request gitlab-org/gitlab!65850

Update issues refactor markup for feature specs

See merge request gitlab-org/gitlab!65861

Add user to top of filtered search in epics

See merge request gitlab-org/gitlab!65608

Add gitaly gem bump danger check

See merge request gitlab-org/gitlab!65325

Review and update security and compliance permissions

See merge request gitlab-org/gitlab!65328

Update Gitaly version

See merge request gitlab-org/gitlab!65953

Replace sucess btn to confirm btn in the preference page

See merge request gitlab-org/gitlab!65836

Adjustments to compare caching

See merge request gitlab-org/gitlab!65839

Fix broken UI link for manual jobs

See merge request gitlab-org/gitlab!65682

Set up trial reassurances experiment & add simple version of sidebar [RUN ALL RSPEC] [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!61639

The upload file service sends a post request
to the URL defined in the uploadsPath parameter
and parses the HTML response to extract
the src and canonicalSrc of the uploaded attachment

Refactor getParameterByName

See merge request gitlab-org/gitlab!65441

Advanced Search: Fix inaccessible ES server error

See merge request gitlab-org/gitlab!65731

Update Gitaly version

See merge request gitlab-org/gitlab!65950

In the preferences page under profile picture in the top navigation,
there is a success button that is deprecated.

Changelog: fixed

Add issues.upvotes_count column

See merge request gitlab-org/gitlab!65250

Add policy type filter

See merge request gitlab-org/gitlab!65500

Fix spec description in abuse_reports_controller

See merge request gitlab-org/gitlab!63946

Rename file path and add change links

See merge request gitlab-org/gitlab!65814

Make job_token_scope_enabled project setting false by default

See merge request gitlab-org/gitlab!64962

Changelog: changed

Added count padding to board list

See merge request gitlab-org/gitlab!65364

Optimised the hash retrieval from URL

See merge request gitlab-org/gitlab!65854

Changed permissions to role

See merge request gitlab-org/gitlab!65671

Allow copying Epic reference from sidebar [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!65550

Update tests for design to support default branch

See merge request gitlab-org/gitlab!65271

Add rollout issue for instance_security_dashboard

See merge request gitlab-org/gitlab!65928

Follows-up: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/63793

Delete legacy operations feature flags records

See merge request gitlab-org/gitlab!63742

Support enable button for DS in config page

See merge request gitlab-org/gitlab!64710

Changelog: added
EE: true