Expose observability port for gitlab-kas

What does this MR do?

Updates gitlab-kas to the latest version and exposes the observability port (prometheus, pprof, readiness and liveness checks).

Related issues

Relates to #2318 (closed). This will be partially solved because it needs this port too.

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes => #2318 (comment 444658864)
• [-] Documentation created/updated - N/A
• [-] Tests added
• [-] Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened