Backup spec: Restrict crypto algorithms in FIPS mode

What does this MR do?

Backup spec: Restrict crypto algorithms in FIPS mode

Restrict crypto settings if operating in FIPS mode. This is needed because we now further enforce FIPS behavior and CI restores a non-FIPS backup into FIPS environments.

Related issues

Relates https://gitlab.com/gitlab-org/build/CNG/-/issues/779

Author checklist

For general guidance, please follow our Contributing guide.

Required

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

• Merge Request Title and Description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch.
• MR has a green pipeline.
• Documentation created/updated.
• Tests added/updated, and test plan for scenarios not covered by automated tests.
• Equivalent MR/issue for omnibus-gitlab opened.

Test Plan

CI passes with images enforcing stronger FIPS behavior: !3963 (comment 2171217864)

Reviewers checklist

• MR has a green pipeline on https://gitlab.com/gitlab-org/charts/gitlab.
• Consider downstream impact to the Operator, as per evaluating impact from changes to GitLab Chart.