Merge branch '2518-persisted-issue-boards-filter-be' of gitlab.com:gitlab-org/gitlab-ee into edit-board

Add notes on authentication to PG HA document

Closes omnibus-gitlab#2735

See merge request gitlab-org/gitlab-ee!2851

Do not clone the repo when running the review-docs jobs

See merge request gitlab-org/gitlab-ee!3000

Resolve "Error 500 due to promote group Web hooks"

Closes #3498

See merge request gitlab-org/gitlab-ee!2972

UX guide update w/ new icon set

See merge request gitlab-org/gitlab-ee!2990

Adds gitlab features and components to usage ping data.

See merge request gitlab-org/gitlab-ee!2956

Fix delta size check to handle commit or nil objects

Closes #3446

See merge request gitlab-org/gitlab-ee!2976

[ci skip]

[ci skip]

Update database.md Geo docs to clarify Postgres needs to be manually restarted

See merge request gitlab-org/gitlab-ee!2992

Previously, we checked out the branch and ran the script from there.
However, when the MR got merged and the cleanup job was run it would
fail since it could not find the now deleted branch.

This commit rather downloads the script from GitLab and skips
downloading the artifacts/dependencies/cache to speed up the process.

Upgrade Nokogiri because of CVE-2017-9050

See merge request gitlab-org/gitlab-ee!2996