Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Clean up opnfv ansible vars and switch to lowercase

    This change removes the variables that are not used in any of the
    playbooks/roles from opnfv ansible vars.

    Apart from that, all caps ansible vars replaced with lowercase ones
    and impacted playbooks/roles are updated.

    installer-type:osa
    deploy-scenario:os-nosdn-nofeature

    Change-Id: I99ebdc155b3903176ac5940b64cef0c0f3aa0f0d
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>