* 9-1-stable:
  Merge branch 'fix-trace-encoding' into 'master'

Explicitly give Encoding.default_external for trace

Closes #30796

See merge request !10728

* 9-1-stable:
  Merge branch 'sh-disable-cache-classes' into 'master'
  Merge branch 'sh-fix-base-parser' into 'master'
  Merge branch 'fix-appending-state-to-issuable-references' into 'master'
  Merge branch '30622-resolve-note-loading-icon-gone' into 'master'
  Merge branch 'clear-instructions' into 'master'
  Merge branch 'sh-improve-logging-for-bad-creations' into 'master'
  Merge branch 'sh-add-icon-for-active-service-template' into 'master'
  Merge branch 'pms-lighter-colors' into 'master'
  Merge branch 'issues-empty-state-not-centered' into 'master'
  Merge branch 'notebook-katex-rendering-improvements' into 'master'
  Merge branch 'zero-downtime-migrations' into 'master'
  Update VERSION to 9.1.0-rc2

Turn on caching of classes in Knapsack specs

See merge request !10709

Fix regression in rendering Markdown references that do not exist

Closes #30972

See merge request !10716

Fix typo: NotImplemented -> NotImplementedError

See merge request !1634

Rename build minutes to pipeline minutes

Closes #2139

See merge request !1644

Fix pipeline quota link

Closes #2158

See merge request !1648

Fix appending state to issuable references

Closes #30874

See merge request !10683

Resolve "Resolve note loading icon gone"

Closes #30622

See merge request !10628

Make instructions clearer

See merge request !10685

Improve error messages when a record is unable to be created for a project

See merge request !10696

Use an icon to indicate whether service template is active

See merge request !10694

Add lighter colors and fix existing light colors

See merge request !10690

Centered empty state for issues

Closes #30872

See merge request !10689

Correctly parse katex math in IPyhton notebooks

Closes #30900

See merge request !10678

Prepare for zero downtime migrations

See merge request !9976

* 9-1-stable:
  Merge branch 'revert-a0d734c9' into 'master'

Revert "Merge branch 'grpc-1.2.2' into 'master'"

See merge request !10700

Fix registry for projects with uppercases in path

Closes #30880

See merge request !10674

After Trace#limit, we seek to the next line in case

Closes #30796

See merge request !10681

* 9-1-stable:
  Merge branch 'docs-add-auth-to-topics-page' into 'master'
  Merge branch 'docs-topic-auth' into 'master'
  Merge branch '27755-update-pipelines-documentation' into 'master'
  Merge branch 'rs-fix-already-defined-constant' into 'master'
  Merge branch 'change-merged-icon' into 'master'
  Merge branch 'grpc-1.2.2' into 'master'
  Merge branch 'fix-missing-capitalisation-buttons' into 'master'
  Merge branch 'improve-discussions-feature-attempt-1' into 'master'
  Merge branch 'siemens/gitlab-ce-fix/subgroup-hide-button' into 'master'
  Merge branch 'backport-ee-1525' into 'master'
  Merge branch 'use-avatars-in-activity-view' into 'master'
  Merge branch '30457-expire-note-destroy' into 'master'
  Merge branch 'patch-15' into 'master'
  Merge branch '30642-fix-recent-search-history-icon-alignment-in-safari' into 'master'
  Merge branch 'zj-api-fix-build-events' into 'master'
  Merge branch 'zj-fix-coverage-bug' into 'master'
  Merge branch '30858-system-notes-indent' into 'master'
  Merge branch 'fix-preloading-merge_request_diff' into 'master'
  Update VERSION to 9.1.0-rc1

Resolve "Disable the experimental GitLab elasticsearch indexer checkbox if it's not in $PATH"

Closes #2149

See merge request !1643

Add icon for approvals in MR

See merge request !1641

Resolve "Making it easier to configure approvals in project settings"

Closes #1738

See merge request !1527

Port of use-avatars-in-activity-view to EE

See merge request !1632

Fix Service Desk emails

See merge request !1638

Port of change-merged-icon to EE

See merge request !1640

Fix push rules on Git 2.11

Closes #1736

See merge request !1525

Add auth to topics page

See merge request !10643

Documentation topic: Authentication

Closes #30744

See merge request !10608

Resolve "Update Pipelines documentation"

Closes #27755

See merge request !10600

Fix NUMBER_OF_TRUNCATED_DIFF_LINES re-definition error

See merge request !10664

Update merged icon

See merge request !10635

Use gRPC 1.2.2

Closes #30766

See merge request !10589

Fixed missing capitalisation on buttons

See merge request !10631