Backport "Remove deprecated templates endpoints in V4"

See merge request !1214

[EE] Resolve "GroupsController#activity.json is REALLY slow due to SQL"

See merge request !1226

CE upstream

Closes gitlab-com/gitlab-docs#68 and #1051

See merge request !1225

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Also, don't use limit in subquery, MySQL don't like that.
Signed-off-by: Rémy Coutable <remy@rymai.me>

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

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

# Conflicts:
#   app/models/repository.rb

[EE] Update Rubocop to Ruby 2.3

See merge request !1195

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

CE Upstream - Friday

Closes gitlab-ce#27955

See merge request !1218

Add member: Always return 409 when a member exists

See merge request !1215

Updated issue boards docs

Closes #27872

See merge request !9097

Add member: Always return 409 when a member exists

Closes #20732

See merge request !9093

removes grayish blue color for events activity

Closes #27608

See merge request !9179

Gather issuable  metadata to avoid n+ queries on index view

Closes #25900

See merge request !9006

The EE version of the protected branches JS doesn't take a label...

We should really reduce the disrepancies between CE and EE for this
feature.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Update Rubocop to Ruby 2.3

See merge request !8994

Move merge requests index file inside the merge_requests dir

See merge request !9181

[ci skip]

Fix issue from milestone

See merge request !8895

Add method for creating foreign keys concurrently

See merge request !9069

Rename Files::DeleteService to Files::DestroyService

See merge request !9110

Resolve "Improve blockquote formatting in notification emails"

Closes #28029

See merge request !9157

Port of "clean-javascript-vendor-files" to EE

See merge request !1223

Convert some vendored javascript assets to npm modules

See merge request !8990

Squashed commit of the following:
    convert js-cookie dependency to an npm module
    convert timeago.js dependency to an npm module
    remove vue from vendor since it is now in node_modules

Fix bundle tag in anaytics page

See merge request !1222

fixes MR widget jump

Closes #27994

See merge request !9146