Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "Create the prepare-tests playbook"
  - Create the prepare-tests playbook

    This playbook should be executed in case we want to use the osa deployment
    as platform for testing a scenario. The playbook currently includes a call
    to the prepare-functest role which installs and sets-up everything to run
    functest based tests

    Change-Id: Ibb59825e64c5889f36fd3bfb38a4d23b67b11866
    Signed-off-by: Manuel Buil <mbuil@suse.com>