[Feature flag - Cleanup] Remove `webauthn_without_totp` feature flag

webauthn_without_totp was rollout to all users of GitLab on the 9ht March 2023 (15.10). No complaints have been reported, so we assume we can remove the webauthn_without_totp feature flag.

Owners

• Team: groupauthentication
• Most appropriate slack channel to reach out to: #g_manage_auth
• Best individual to reach out to: @tachyons-gitlab @eduardosanz
• PM: @hsutor

Stakeholders

Expectations

What might happen if this goes wrong?

Cleaning up the feature flag

• Create a merge request to remove webauthn_without_totp feature flag. Ask for review and merge it.
  • Remove all references to the feature flag from the codebase.
  • Remove the YAML definitions for the feature from the repository.
  • Create a changelog entry.
• Ensure that the cleanup MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post.
  • /chatops run auto_deploy status <merge-commit-of-cleanup-mr>
• Close the feature issue to indicate the feature will be released in the current milestone.
• If not already done, clean up the feature flag from all environments by running these chatops command in #production channel:
  • /chatops run feature delete webauthn_without_totp --dev
  • /chatops run feature delete webauthn_without_totp --staging
  • /chatops run feature delete webauthn_without_totp
• Close this rollout issue.