the ci status icons are generated client side, wo we don't need the
static files anymore.

the initial reason for this change was that graphicsmagick does not
support writing to ico files. this fact lead to a chain of changes:

1. use png instead of ico (browser support is good enough)
2. render the overlays on the client using the canvas API. this way we
   only need to store the original favion and generate the overlay versions
   dynamically.
   this change also enables (next step) to simplify the handling of the
   stock favicons as well, as we don't need to generate all the versions
   upfront.

this ways we can keep the `lib/gitlab/ci/status/*` classes to return the
bare favicon name as it was before.

also the favicon uploader versions are now have the same names as the
stock favicons (+ `favicon_` prefix), which makes working with the
status names easier.

Without the '?' at the end of the favicon url the custom favicon (i.e.
the favicons that are served through `UploadController`) are not shown
in the browser. It may have something to do with how `#send_file` /
`#send_data` set http headers. When serving the same icon file from the
public directory everything is fine.

`#send_file` won't properly set the favicon's content type otherwise.

when versions have a different file format from the original file
carrierwave constructs a wrong url (with the original file suffix).

Add Configuration team to the list

See merge request gitlab-org/gitlab-ce!19416

Prevent Gitaly WriteConfig log noise

Closes gitaly#1221

See merge request gitlab-org/gitlab-ce!19375

Add background migrations to archive legacy job traces

Closes #46642

See merge request gitlab-org/gitlab-ce!19194

Also verify if extending would override a class method

See merge request gitlab-org/gitlab-ce!19377

Resolve "NoMethodError: undefined method `previous_changes' for nil:NilClass"

Closes #46452

See merge request gitlab-org/gitlab-ce!19190

Perform pull request IO work outside a transaction

See merge request gitlab-org/gitlab-ce!19372

Update security products job and artifact names in documentation.

See merge request gitlab-org/gitlab-ce!19315

Support rails5 in postgres indexes function and fix some migrations

Closes #46236

See merge request gitlab-org/gitlab-ce!19400

Fix Rubocop offense in build specs

See merge request gitlab-org/gitlab-ce!19419

Optimise pages service calling

See merge request gitlab-org/gitlab-ce!19388

Bring CE-EE parity to app/services/projects/update_service.rb

See merge request gitlab-org/gitlab-ce!19117

Eliminate N+1 queries for CI job artifacts in /api/projects/:id/pipelines/:pipeline_id/jobs

See merge request gitlab-org/gitlab-ce!19353

Resolve "Add Xcode Button in UI"

Closes #45820

See merge request gitlab-org/gitlab-ce!19406

Fixed alignment issues with IDE sidebar

Closes #47244

See merge request gitlab-org/gitlab-ce!19272

Fix jobs log background color

Closes #47261

See merge request gitlab-org/gitlab-ce!19411

[Rails5] Update Gemfile.rails5.lock

See merge request gitlab-org/gitlab-ce!19405