Ensure advisory db updated at scan time

What does this MR do?

This MR ensures that the ruby advisory db on which the bundler-audit scanner relies is always updated at scan time.

This change is tested in various configurations in this ruby-bundler branch: https://gitlab.com/gitlab-org/security-products/tests/ruby-bundler/-/pipelines/267382354

After approval, the branch will become a FREEZE branch.

What are the relevant issue numbers?

gitlab-org/gitlab#322925 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer