Update git submodules

Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Fixes nova migration

    Nova migration was failing in rally sanity test.  Looking at the keys
    nova is configured with, the newlines in the private key were being
    converted to spaces in hieradata, thus making the key invalid.  This
    patch corrects the yaml so it is multiline data.

    Also, corrects the parameter being set to the right THT parameter and
    adds sshd service to the control/compute roles which is required for
    migration to work.

    JIRA: APEX-525

    Change-Id: Ic57db5c0b27df2e1f584f3c1a379e067291d892d
    Signed-off-by: Tim Rozet <trozet@redhat.com>
    (cherry picked from commit 8a8cb8e901db314fa59ed5275040b9e49b36663c)