Change Prometheus metrics names

Closes #3114

See merge request gitlab-org/gitlab-runner!912

Explain gitlab-runner workflow labels

See merge request gitlab-org/gitlab-runner!921

Add link to development guide in readme

Closes #3122

See merge request gitlab-org/gitlab-runner!918

Closes https://gitlab.com/gitlab-org/gitlab-runner/issues/3122

Document how check_interval works

Closes #3190

See merge request gitlab-org/gitlab-runner!903

Fix test file archiver tests

See merge request gitlab-org/gitlab-runner!915

Rename CI_COMMIT_REF to CI_COMMIT_SHA

See merge request gitlab-org/gitlab-runner!911

Do not send first PUT

See merge request gitlab-org/gitlab-runner!908

Originally, this value was `$CI_BUILD_REF`, and deprecated in 9.0 to
become `$CI_COMMIT_SHA`. The value being set by the exec runner is
`$CI_COMMIT_REF`, which does not appear to have ever been a valid
name.

* 10-8-stable:
  Update CHANGELOG for v10.8.0
  Update CHANGELOG for v10.8.0-rc3
  Merge branch 'fix-panic-on-patch-trace' into 'master'
  Update CHANGELOG for v10.8.0-rc2
  Merge branch '3244-add-missing-tzdata-package-to-ubuntu-image' into 'master'

Fix panic on PatchTrace execution

See merge request gitlab-org/gitlab-runner!905

Fix panic on PatchTrace execution

See merge request gitlab-org/gitlab-runner!905

Update virtualbox.md temporary fix for #2981

See merge request gitlab-org/gitlab-runner!889

Start rename of "metrics server" config

Closes #3096

See merge request gitlab-org/gitlab-runner!838

Resolve "Invalid OffPeakPeriods value, no such file or directory."

Closes #3244

See merge request gitlab-org/gitlab-runner!897

Add --paused option to register command

Closes #2045

See merge request gitlab-org/gitlab-runner!896

Resolve "Invalid OffPeakPeriods value, no such file or directory."

Closes #3244

See merge request gitlab-org/gitlab-runner!897

Add new metrics related to jobs requesting and API usage

See merge request gitlab-org/gitlab-runner!886