Changes

jobs/gerrit: use deps cache from docker image

Instead of freshly cloning the dependencies each time, use the cache we
already have in the debian-bookworm-titan docker image. This way only
the dependency repositories that were changed in the patch submitted to
gerrit need to be updated.

Related: OS#6572
Change-Id: I895011edf49f612d0df7f4759dc374bab60c32a6