Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: scripts: start-new-vm.sh: Do not run multiple package manager processes"
  - xci: scripts: start-new-vm.sh: Do not run multiple package manager processes

    Package managers get upset if multiple instances run in parallel since
    the last one will fail to aquire some sort of DB locking and fail. As
    such, lets fix that and only run one package manager process at any
    time.

    Change-Id: I4ab13f61eee861ef70cb4115403d0e239ec14308
    Signed-off-by: Markos Chandras <mchandras@suse.de>