CE upstream: Friday

Closes gitlab-ce#39188, gitaly#683, #3664, and gitlab-ce#39351

See merge request gitlab-org/gitlab-ee!3214

EE: Fetch the merged branches at once

See merge request gitlab-org/gitlab-ee!3204

Update EE docs to allow not having EE namespace

See merge request gitlab-org/gitlab-ee!3194

* upstream/master: (72 commits)
  Avoid using Rugged in Gitlab::Git::Wiki#preview_slug
  Cache commits on the repository model
  Remove groups_select from global namespace & simplifies the code
  Change default disabled merge request widget message to "Merge is not allowed yet"
  Semi-linear history merge is now available in CE.
  Remove repetitive karma spec
  Improve spec to check hidden component
  Rename to shouldShowUsername
  Add KubernetesService#default_namespace tests
  Revert "Merge branch '36670-remove-edit-form' into 'master'"
  Fix bitbucket login
  Remove duped tests
  Add path attribute to WikiFile class
  Make local_branches OPT_OUT
  Clarify the language around External Group membership with SAML SSO to clarify that this will NOT add users to GitLab Groups.
  Added ssh fingerprint, gitlab ci and pages information in an instance configuration page
  Fix the incorrect value being used to set GL_USERNAME on hooks
  Resolve "Remove overzealous tooltips in projects page tabs"
  Fix broken table of content links
  Remove filter icon from search bar
  ...

Geo: Ensure database is connected before attempting to check for secondary status

Closes #3074

See merge request gitlab-org/gitlab-ee!3112

Cache commits on the repository model

See merge request gitlab-org/gitlab-ce!14863

Avoid using Rugged in Gitlab::Git::Wiki#preview_slug

See merge request gitlab-org/gitlab-ce!15054

Add configurable option to display username in user avatar link component

See merge request gitlab-org/gitlab-ce!14902

EE - Remove groups_select from global namespace & simplifies the code

See merge request gitlab-org/gitlab-ee!3203

Sanitize k8s default_namespace

Closes #38692

See merge request gitlab-org/gitlab-ce!15053

Change default disabled merge request widget message to be more general -- EE merge edition

Closes gitlab-ce#39188

See merge request gitlab-org/gitlab-ee!3180

Revert "Merge branch '36670-remove-edit-form' into 'master'"

Closes #39441

See merge request gitlab-org/gitlab-ce!15049

Revert "Merge branch '36670-remove-edit-form' into 'master'"

See merge request gitlab-org/gitlab-ee!3208

Change default disabled merge request widget message to be more general

Closes #39188

See merge request gitlab-org/gitlab-ce!14960

Now, when requesting a commit from the Repository model, the results are
not cached. This means we're fetching the same commit by oid multiple times
during the same request. To prevent us from doing this, we now cache
results. Caching is done only based on object id (aka SHA).

Given we cache on the Repository model, results are scoped to the
associated project, eventhough the change of two repositories having the
same oids for different commits is small.

* master: (139 commits)
  btn-small -> btn-sm
  Merge branch 'fix-application-setting-nil-cache' into 'master'
  no CI replication
  [CE->EE] Resove frontent conflicts
  [CE->EE] Fix wrong resolvation of specs
  [CE->EE] Resolve group routes
  [CE->EE][ci skip] Resolve conflicts
  Resolve conflict in lib/backup/manager.rb
  Resolve conflict in .gitlab-ci.yml
  [CE->EE][ci skip] Resolve conflicts
  [CE->EE][ci skip] resolve frontend conflicts
  Remove `<script>` and `<template>` from CHANGELOG.md
  Simple docs fixes
  Fix button type
  Changes after review
  Removes group_avatar & group_label_subscription from global namespace
  Fix CSS in load more participants
  Fix the description of the new branch created by an issue's new branch button
  Fix a small typo in the delete merged branches documentation
  Moves vue resource docs into a new file. Adds docs regarding handling 204 response
  ...

Semi-linear history merge is now available in CE.

See merge request gitlab-org/gitlab-ce!15059

Remove groups_select from global namespace & simplifies the code

See merge request gitlab-org/gitlab-ce!15008

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/39188

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/39188

Already mentioned in the list above this one.

btn-small -> btn-sm

Closes #3637

See merge request gitlab-org/gitlab-ee!3210

This reverts commit 915e35a2, reversing
changes made to 9533786f.

Fix bitbucket login

Closes #39495

See merge request gitlab-org/gitlab-ce!15051

CE upstream

Closes #3794, #3781, gitaly#638, and gitlab-ce#38923

See merge request gitlab-org/gitlab-ee!3199

Fix broken table of content links

Closes #39471

See merge request gitlab-org/gitlab-ce!15034

If the database connection were severed, a secondary may not reattempt to
establish a connection to the database. We now always called `GeoNode.exists?`
to ensure ActiveRecord maintains a connection. In the Geo initializer, avoid
establish a connection in case a Rake task is called.

Closes #3074

This reverts commit 915e35a2, reversing
changes made to 9533786f.

Clarify the language around External Group membership with SAML SSO to clarify…

See merge request gitlab-org/gitlab-ce!15042

Likely caused by EE conflicts resolution