Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "jjb: xci: Add postbuild publisher script to remove clean VM"
  - jjb: xci: Add postbuild publisher script to remove clean VM

    The clean VM normally stays around after the job is completed or killed
    due to timeout. Unless a job for the same distro is scheduled on the
    same node, that VM will state around for a while consuming valuable
    system resources. As such, we should remove it after the job finishes
    to free up resources for the new jobs.

    Change-Id: I88b5e32797969d9378588199a7ddb013bbe740c9
    Signed-off-by: Markos Chandras <mchandras@suse.de>