Backport of 'Stop failing on stale browser console allowlist specs' into 19.5

What does this MR do and why?

This MR backports !262015 (merged) to 19.5. It is a clean cherry-pick of the default branch commit 47b3fab0, and the diff is identical. It changes one spec file and no application code.

On 19-5-stable-ee, spec/support_specs/browser_console_allowlist_spec.rb fails in the as-if-FOSS pipeline. The allowlist names ee/ feature specs, and those paths match no file in the FOSS build. All 20 examples fail. !262015 (merged) removed the check that each path matches a file, because a stale path has no effect at runtime.

The failure blocks 19.5 backports whose MR pipeline runs the as-if-FOSS pipeline. For example, the start-as-if-foss pipeline of !262206 (merged) failed with these 20 examples in rspec unit pg17 29/35 (job).

Testing

On a GDK sandbox at this branch's head, spec/support_specs/browser_console_allowlist_spec.rb ran 214 examples with 0 failures. rubocop on the changed file reports no offenses.

Pushed with pre-push hooks skipped (LEFTHOOK=0). The hooks in lefthook.yml compute their file list from git merge-base origin/master HEAD, so on a stable branch they lint every file where 19.5 differs from master. The checks that apply to this change ran on the sandbox instead.

MR acceptance checklist

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

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• The MR title is descriptive (e.g. "Backport of 'title of default branch MR'"). This is important, since the title will be copied to the patch blog post.
• Required labels have been applied to this merge request
  • severity label and bug subtype labels (if applicable)
  • If this MR fixes a bug that affects customers, the customer label has been applied.
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the E2E Omnibus GitLab EE pipeline (triggered by thee2e:test-on-omnibus-ee job) has succeeded. If it has failed (or shows warnings), investigate the failures. If you determine the failures are unrelated, you may proceed. If you need assistance investigating, request help in the #s_developer_experience Slack channel to confirm the failures are unrelated to the merge request.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).
• Once the backport has been merged, the commit changes will be automatically deployed to a release environment that can be used for manual validation. See after merging runbook for details.