Update selenium-webdriver to 3.12.0

Closes #47183

See merge request gitlab-org/gitlab-ce!19351

Fix bootstrap 4 file inputs

Closes #46701

See merge request gitlab-org/gitlab-ce!19333

Add comment about the need for truncating keys in Ruby 2.4

See merge request gitlab-org/gitlab-ce!19330

[ci skip]

Use RequestStore to memoize Flipper features so that memoized values are cleared between requests

See merge request gitlab-org/gitlab-ce!19281

https://gitlab.com/gitlab-org/gitlab-ce/-/jobs/71887977 was failing
due to confusion between Ci::Group and Group.
https://gitlab.com/gitlab-org/gitlab-ce/-/jobs/71887977

Upgrade to Ruby 2.4.4

See merge request gitlab-org/gitlab-ce!19055

Revert "Merge branch '46833-sticky-polyfill' into 'master'"

See merge request gitlab-org/gitlab-ce!19322

Resolve "Branch names in system notes have incorrect color"

Closes #46696

See merge request gitlab-org/gitlab-ce!19296

Bump omniauth-gitlab to 1.0.3

See merge request gitlab-org/gitlab-ce!19319

This reverts merge request !19304

Adds "the" to the new label page to correct the sentence.

See merge request gitlab-org/gitlab-ce!19316

Update position sticky polyfill

Closes #46833

See merge request gitlab-org/gitlab-ce!19304

This version of the gem uses API v4 by default:

https://github.com/linchus/omniauth-gitlab/commit/fd13de9f251fdaa72ba0195bda47cd2cb8731084

Resolve "Modal header styling is broken"

Closes #47113

See merge request gitlab-org/gitlab-ce!19312

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

Update FE guides with dependency/devDependency distinction

See merge request gitlab-org/gitlab-ce!19287

CE: Part of "Extract EE specific files/lines for app/views/shared/issuable"

See merge request gitlab-org/gitlab-ce!19113

Resolve "The font is too bold in Issue events tab on Activity page"

Closes #46619

See merge request gitlab-org/gitlab-ce!19291

Resolve "Update `updated_at` on an issue/mr on every issue/mr changes"

Closes #46478

See merge request gitlab-org/gitlab-ce!19065

Resolve "Admin area > Monitoring > Logs > No default active tab"

Closes #46815

See merge request gitlab-org/gitlab-ce!19298

Make http_io honor HTTP(S)_PROXY environment.

Closes #46968 and #46982

See merge request gitlab-org/gitlab-ce!19282

ReactiveCaching#clear_reactive_cache! should not keep the cache alive

See merge request gitlab-org/gitlab-ce!19311