refactor: Follow-ups to glpat auto-revocation

What does this MR do and why?

Some cleanup follow-ups as documented in #371658 (comment 1175310397). See each commit for individual change explanation. Summary:

• chore: Cleanup revocation_permitted? check to better represent permission attribution and callback to source as self
• chore: Deduplicate revocation of glpat tokens to prevent excess revocations of the same token regardless of occurrences in a pipeline report
• chore: Add explanatory code comment to revocation svc key type
• feat: Improve audit trail with User.security_bot attribution on auto-revocation
• feat: Include explanatory comment on Vulnerability page attributing auto-revocation

Screenshots

feat: Improve audit trail with User.security_bot attribution on auto-revocation

before	after

feat: Include explanatory comment on Vulnerability page attributing auto-revocation

Note that the state should remain "needs triage" for awareness, only the comment is added

before	after

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.