CE upstream

Closes gitlab-ce#27674

See merge request !1170

CE upstream

Closes #395

See merge request !1161

Add index to labels for `type` and project_id`

Closes #27676

See merge request !8978

Fixed typo in slash commands docs

Closes #27674

See merge request !8976

Fix "NameError: uninitialized constant Rack::Proxy" in production environment

See merge request !1168

When loading pages that display the number of open issues,
the backend runs a query such as:

```sql
SELECT "labels"."id" FROM "labels" WHERE "labels"."type" IN ('ProjectLabel') AND "labels"."project_id" = 1000
```

This results in an entire scan of the `labels` table. To optimize performance,
add the appropriate index to the table.

Closes #27676

Fix "NameError: uninitialized constant Rack::Proxy" in production environment

See merge request !8977

Fixes gitlab-org/gitlab-ce#27674

UX Guide: Button placement in groups

See merge request !8972

Integrate webpack for frontend asset compilation

Closes #14634

See merge request !7288

Port "Integrate webpack for frontend asset compilation" to EE

See merge request !1138

* master: (54 commits)
  Move project services to new location under Integrations
  Move webhooks to new a location under Integrations
  Fix documentation link in doc/user/project/pages/index.md
  Fixed merge request widget tests
  Small documentation changes and fixes for Geo
  Remove ‘EE-specific’ comments related to Pages feature
  Update specs with new method signatures
  rm_tag now takes a user argument
  Use GitOperationService instead
  Merge remote-tracking branch 'ce/fix-git-hooks-when-creating-file' into master-ce
  Mentioned pages to CE port in project/pages/index.md
  Fixed merge request environment not displaying
  Update guidance on handling shared secrets in HA setup
  Pull EE specific Gitlab::Auth code in to its own module
  Use `add_$role` helper in snippets specs
  Check public snippets for spam
  Keep snippet visibility on error
  Add info on using both push/pull repository mirroring
  Properly read approvalPending from dataset.
  Fix data attr spacing.
  ...

Document that the retro and kickoff notes are public

See merge request !8788

* master:
  Change window size before visiting page, to get correct scroll position
  Fix slash commands spec error
  Move project services to new location under Integrations
  Move webhooks to new a location under Integrations
  Fixed eslint test failure
  Fixed redirection from http://someproject.git to http://someproject
  Add traits for the different Event types to the Event factory
  prevent nonewline type diff lines from containing unfolding link
  ensure linenumber data attribute is correct for the last line in a diff chunk
  ensure last line in diff block is contained within a table row element
  ensure click event is bound only once