Recommend against the use of EFS

See merge request gitlab-org/gitlab-ee!3897

EE changes after moving fast authorized_keys feature to CE

See merge request gitlab-org/gitlab-ee!3959

The spec for "#add_key does nothing" would always have passed,
since the expectation was on both the wrong object and message.

Geo admin screen enhancements

Closes #4268, #4179, and #1363

See merge request gitlab-org/gitlab-ee!3902

EE: Run background migrations with a minimum interval

Closes gitlab-ce#41624

See merge request gitlab-org/gitlab-ee!3933

Document GitLab Geo with Object Storage

Closes #3944

See merge request gitlab-org/gitlab-ee!3760

EE: Remove unused push_code_to_protected_branches

See merge request gitlab-org/gitlab-ee!3955