Make sign-artifacts only for maven-stage

This maven-docker-stage job does not need
to run sigul right now since the job only
tries to sign JAVA artifacts and not docker
images.

Issue-ID: CIMAN-33
Signed-off-by: Vanessa Rene Valderrama <vvalderrama@linuxfoundation.org>
Change-Id: I778f0b0b0fdeb080a3370fbd4fc5b876a3bfeb73
10 files changed