Merge branch '402984-start-using-gitlab-zoekt-indexer' into 'master'

Change Zoekt to use Gitaly for fetching code

See merge request !122308



Merged-by: John Mason <9717668-johnmason@users.noreply.gitlab.com>
Approved-by: Madelein van Niekerk <mvanniekerk@gitlab.com>
Approved-by: Ash McKenzie <amckenzie@gitlab.com>
Approved-by: Jennifer Li <jli@gitlab.com>
Approved-by: John Mason <9717668-johnmason@users.noreply.gitlab.com>
Reviewed-by: Ash McKenzie <amckenzie@gitlab.com>
Co-authored-by: Dmitry Gruzd <dgruzd@gitlab.com>