Add default category for shared example

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/179890



Merged-by: Jonas Larsen <jlarsen@gitlab.com>
Approved-by: Pedro Pombeiro <noreply@pedro.pombei.ro>
Approved-by: Jonas Larsen <jlarsen@gitlab.com>
Co-authored-by: syasonik <syasonik@gitlab.com>