Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: scripts: start-new-vm.sh: Rework fix for parallel pkg mgr instances"
  - xci: scripts: start-new-vm.sh: Rework fix for parallel pkg mgr instances

    The current way of detecting whether multiple package manager processes
    are running is not ideal so just wait a random amount of time if we
    detect that another instance of our package manager command is running.

    Change-Id: Id94e3ed5293bf223f7250f92525a6e02bb1ea842
    Signed-off-by: Markos Chandras <mchandras@suse.de>