testrunner P_VDSM path fix

when running run_tests_local.sh the tests that want to find modules
that would usually be installed to /usr/share/vdsm should look in
$repo_root/vdsm instead of $repo_root.

Change-Id: I7ce18ceacbf95813c587238863e271f200322478
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/20020
Reviewed-by: mooli tayer <mtayer@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>