Moved shared date & time formats into constants

Merge remote-tracking branch 'origin/26914-deploy_history_data_source' into metrics-deployment-history

Fix PlantUML integration in GFM

Closes #30557

See merge request !10651

Use constants in Gitlab::MarkupHelper

See merge request !10741

Refactor changing files in web UI

Closes #28711

See merge request !9323

Add retries to system hook worker

Closes #31109

See merge request !10801

Don't delete a branch involved in an open merge request in "Delete all merged branches" service

Closes #29427

See merge request !10727

The default number of Sidekiq retries is 25 over about 21 days.
If an external system is unavailable for a length of time, hooks
can pile up in the Sidekiq queues. If the situation gets bad enough
the retry jobs dropping back into the main queue can slow down
other jobs. Limit the retries to a sane number to avoid this
scenario.

Resolve "start discussion toggle clicking divider causes UI break"

Closes #30951

See merge request !10715

Add unique index to system note metadata

See merge request !10774

Implement search by extern_uid in Users API

See merge request !10509

Add renderNote animation and added spec

Closes #29977

See merge request !10623

Set the issuable sidebar to remain collapsed on mobile devices

Closes #28086

See merge request !10323

Fixed branches sort toggle being empty

Closes #30950

See merge request !10764

Removed target blank from the environments component

Closes #31029

See merge request !10726

Update groups.md found typo

See merge request !10792

Fixed group milestones date pickers not working

Closes #31095

See merge request !10779

Added profile name to user dropdown

Closes #30484

See merge request !10469

Merge branch '29734-prometheus-monitoring-page-displays-button-to-control-manual-actions' into 'master'

Remove manual deployment controls from Environment metrics page

Closes #29734

See merge request !10769