Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge changes from topic 'stable-branch'

    * changes:
      [armband] verify: Simplify and move to build hosts
      [fuel] Retire Danube stream
      [fuel] cleanup: remove unused scenarios
      [fuel] cleanup: remove unused job defs & scripts

  - [armband] verify: Simplify and move to build hosts

    Now that Fuel verify jobs cover arm64 deployments by default, we
    only need to validate that the Armband patches still apply on top
    of the latest Fuel@OPNFV git submodule HEAD.

    While at it, tweak timed trigger order.

    JIRA: ARMBAND-401

    Change-Id: I4ed20b52906848efff6bad641852d3dd1bee3db3
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
  - [fuel] Retire Danube stream

    - cleanup deploy tooling for old-style artifacts (ISO-based);
    - remove danube stream, related jobs and hacks required for them;

    Change-Id: Ib2486173df1ec83f2dbc08a5e9faf950bffb4b06
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
  - [fuel] cleanup: remove unused scenarios

    We don't currently support ONOS and KVM-based scenarios.

    Change-Id: I9869498c1f726293d571562291e850a817bf3e18
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
  - [fuel] cleanup: remove unused job defs & scripts

    Change-Id: I64aae5719f1a0a667e56722bab9e5012a813571f
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>