Fix Style/SelectByRegexp RuboCop violation

What does this MR do and why?

Resolves Style/SelectByRegexp (https://docs.rubocop.org/rubocop/cops_style.html#styleselectbyregexp) RuboCop violation for project.

Screenshots, screen recordings, or links to review app

• Review app: https://eread-fix-select-by-regexp-rubocop-violation.docs.gitlab-review.app
• compile_dev job generates Kramdown warnings: https://gitlab.com/gitlab-org/gitlab-docs/-/jobs/3787835783.

How to set up and validate locally

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. Check everything builds and renders correctly.

Merge request 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 merge request.