Update git submodules

Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Stop redefine testcases.yaml for some test cases

    1. For Functest healthcheck, patrole, refstack_defcore, neutron_trunk and vping
       test cases, stop to redefine testcases.yaml.
    2. For VNF and bgpvpn, they still have scenario dependencies for Functest.
       How to handle them are still under consideration.
    3. For other tempest test cases, they rely on tempest_custom. Leave them
       under discussion.

    JIRA: DOVETAIL-673

    Change-Id: Ibd10c9883d8df3749f4a93e280deaca77fe6bc00
    Signed-off-by: xudan <xudan16@huawei.com>