Merge branch 'jnutt/group-hook-validation' into 'master'

Delegate GroupHook URL validation to base class

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/154879



Merged-by: Luke Duncalfe <lduncalfe@gitlab.com>
Approved-by: Luke Duncalfe <lduncalfe@gitlab.com>
Reviewed-by: Luke Duncalfe <lduncalfe@gitlab.com>
Co-authored-by: James Nutt <jnutt@gitlab.com>