Merge branch 'bwill/fix-no-method-error-for-x509-signatures' into 'master'

Fix NoMethodError when showing X.509 signature users

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/105283



Merged-by: Igor Drozdov <idrozdov@gitlab.com>
Approved-by: Igor Drozdov <idrozdov@gitlab.com>
Co-authored-by: Brian Williams <bwilliams@gitlab.com>