Reduce UPDATEs for background column type changes

Closes #42158

See merge request gitlab-org/gitlab-ce!16551

Add cache clearing documentation

Closes #41940

See merge request gitlab-org/gitlab-ce!16559

Remove unnecessary query from labels dropdown

Closes #37143

See merge request gitlab-org/gitlab-ce!16520

Resolve "Pipeline stages are jumping when dropdown is open"

Closes #41806

See merge request gitlab-org/gitlab-ce!16556

Added dispatcher imports for some project routes

See merge request gitlab-org/gitlab-ce!16389

[ci skip]

Remove IDE option from user preferences

See merge request gitlab-org/gitlab-ce!16454

[ci skip]

Add Git LFS status icon to docs

See merge request gitlab-org/gitlab-ce!16555

Docs: set comments to false on deprecated articles list doc

See merge request gitlab-org/gitlab-ce!16498

[ci skip]

Fix: fix typo  to open source

See merge request gitlab-org/gitlab-ce!16549

Retrieve commit signatures with Gitaly

Closes gitaly#923

See merge request gitlab-org/gitlab-ce!16467

Remove Rugged::Walker from Repository#log

Closes #42089

See merge request gitlab-org/gitlab-ce!16525

Merge branch '42172-deprecation-warning-timestamps-was-called-without-specifying-an-option-for-null-in-rails-5-this-behavior-will-change-to-null-false' into 'master'

Resolve "DEPRECATION WARNING: `#timestamps` was called without specifying an option for `null`. In Rails 5, this behavior will change to `null: false`..."

Closes #42172

See merge request gitlab-org/gitlab-ce!16545

Fix spec/migrations/update_upload_paths_to_system_spec.rb to use the :migration metadata

See merge request gitlab-org/gitlab-ce!16546

Prior to this commit we would essentially update all rows in a table,
even those where the source column (e.g. `issues.closed_at`) was NULL.
This in turn could lead to statement timeouts when using the default
batch size of 10 000 rows per job.

To work around this we don't schedule jobs for rows where the source
value is NULL. We also don't update rows where the source column is NULL
(as an extra precaution) or the target column already has a non-NULL
value. Using this approach it should be possible to update 10 000 rows
in the "issues" table in about 7.5 - 8 seconds.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/42158

Get rid of a Rails 5 deprecation warning in db/migrate/20170425112128_create_pipeline_schedules_table.rb
Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix Mermaid drawings not loading on some browsers

Closes #42052

See merge request gitlab-org/gitlab-ce!16537

System hooks for Merge Requests

See merge request gitlab-org/gitlab-ce!14387

Fix the user-agent detail API endpoint for project snippets

Closes #42129

See merge request gitlab-org/gitlab-ce!16521

Signed-off-by: Rémy Coutable <remy@rymai.me>

Add modal for stopping jobs in admin area

Closes #41305

See merge request gitlab-org/gitlab-ce!16283

Update ConvDev Index docs w better screenshot

See merge request gitlab-org/gitlab-ce!16533

Add openSUSE to the supported Unix OS list

See merge request gitlab-org/gitlab-ce!16544

Remove a broken link in the docs

See merge request gitlab-org/gitlab-ce!16532

Add the :migration metadata, and don't use factories in FixWronglyRenamedRoutes spec

See merge request gitlab-org/gitlab-ce!16535