Merge remote-tracking branch 'origin/master' into 38759-fetch-available-parameters-directly-from-gke-when-creating-a-cluster

Fix encoding of branch names on compare and new merge request page

Closes #46627

See merge request gitlab-org/gitlab-ce!19143

Upgrade to Bootstrap 4

Closes #45185 and #46710

See merge request gitlab-org/gitlab-ce!18232

Merge branch '46740-projectmilestones-setting-start_date-via-the-api-requires-a-second-parameter' into 'master'

Resolve "ProjectMilestones: Setting start_date via the API requires a second parameter"

Closes #46740

See merge request gitlab-org/gitlab-ce!19133

Authentiq gem update

See merge request gitlab-org/gitlab-ce!19137

Remove Gemnasium badge from project's README.md

Closes #45404

See merge request gitlab-org/gitlab-ce!19136

Remove dead link to Google Drive

See merge request gitlab-org/gitlab-ce!19139

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

See merge request gitlab-org/gitlab-ce!19111

Resolve "gitlab 10.8 assumes that installation is a git working copy."

Closes #46600

See merge request gitlab-org/gitlab-ce!19125

Init documentation for embedded snippets

See merge request gitlab-org/gitlab-ce!19120

Resolve "Typo on the empty Pipelines page"

Closes #46768

See merge request gitlab-org/gitlab-ce!19140

Resolve "Show CI pipeline status in Web IDE"

Closes #44579

See merge request gitlab-org/gitlab-ce!19048

Disable the background Prometheus sampler in tests

See merge request gitlab-org/gitlab-ce!19130