Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'stable/danube'
  - Make tempest cleanup resources after running

    JIRA: FUNCTEST-773

    1. When running refstack_defcore, create tenant and user failed due to conflict
       with those created when runnning tempest_smoke_serial.
    2. Clean all resources created for tempest_smoke_serial.

    Change-Id: Icf8ec95f6db0b2f93bf6c56ec10a6e8ea1a91ab1
    Signed-off-by: Linda Wang <wangwulin@huawei.com>
    (cherry picked from commit f94a1744e7a4d3a48466b6171a205e1ed84026d7)