Enable Fips/MD5 cop in RuboCop

What does this MR do?

Enables Fips/MD5 cop in RuboCop.

Related issues

Relates to #3691

Follows up Update gitlab-styles from 6.2.0 to 9.0.0 (!2769 - merged)

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
• [n/a] Documentation created/updated
• [n/a] Tests added
• [n/a] Integration tests added to GitLab QA
• [n/a] Equivalent MR/issue for omnibus-gitlab opened