Merge branch 'mg-empty-string-matching-20250521' into 'master'

Allow empty string matching in RegEx

See merge request !192082



Merged-by: Heinrich Lee Yu <heinrich@gitlab.com>
Approved-by: Shreyas Agarwal <sagarwal@gitlab.com>
Approved-by: Laura Montemayor <lmontemayor@gitlab.com>
Approved-by: Félix Veillette-Potvin <fveillette@gitlab.com>
Approved-by: Heinrich Lee Yu <heinrich@gitlab.com>
Reviewed-by: Heinrich Lee Yu <heinrich@gitlab.com>
Reviewed-by: Shreyas Agarwal <sagarwal@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Co-authored-by: Manuel Grabowski <mgrabowski@gitlab.com>