Merge branch 'tor/defect/vue-mr-list/missing-filter-options/target-branch-is-not-be' into 'master'

Enable NOT filtering for target branches in MR List GQL

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/170664



Merged-by: Paul Slaughter <pslaughter@gitlab.com>
Approved-by: Amy Qualls <aqualls@gitlab.com>
Approved-by: Paul Slaughter <pslaughter@gitlab.com>
Reviewed-by: Amy Qualls <aqualls@gitlab.com>
Co-authored-by: Thomas Randolph <trandolph@gitlab.com>