Remove pipeline_name_search feature flag

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/133607



Merged-by: Adam Hegyi <ahegyi@gitlab.com>
Approved-by: Ethan Urie <eurie@gitlab.com>
Approved-by: Marcel Amirault <mamirault@gitlab.com>
Approved-by: Ross Byrne <robyrne@gitlab.com>
Approved-by: Adam Hegyi <ahegyi@gitlab.com>
Approved-by: drew stachon <730684-drew@users.noreply.gitlab.com>
Approved-by: James Fargher <jfargher@gitlab.com>
Reviewed-by: Reuben Pereira <2967854-rpereira2@users.noreply.gitlab.com>
Co-authored-by: Reuben Pereira <rpereira@gitlab.com>