gitlab-shell: remove ruby and excess

What does this MR do?

This MR refactors !1062 (merged) to resolve the issues found in gitlab-org/charts/gitlab#3419 (closed)

• gitlab-shell: refactor Dockerfile for layer savings

  Refactor the Dockerfile for savings on the layer count, by moving more operations into the build stage. Some items require very specific permissions, and thus have follow-up COPY entries to ensure ownership by root

• gitlab-shell: fixup /etc/ssh permissions

  Fixup the permissions on /etc/ssh, moving chown to COPY

  👓 This did not work, as seen in a follow change to add a chmod directly 🤷

• gitlab-shell: remove superfluous from process-wrapper

  Remove superfluous "copy to /etc/ssh" when generating new host keys

Details

image	layers	compressed	decompressed
main	21	347 MB	937 MB
shell-remove-ruby-v3	9	110 MB	255 MB
DIFF	12	237 MB	682 MB
main-ubi8	12	233 MB	593 MB
shell-remove-ruby-v3-fips (ubi8)	6	147 MB	381 MB
DIFF	6	86 MB	212 MB

Related issues

Closes gitlab-org/charts/gitlab#2242 (closed)

Relates to gitlab-org/charts/gitlab#3419 (closed)

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
• Documentation created/updated
• Integration tests added to GitLab QA
• The impact any change in container size has should be evaluated