Inner modules called by the kolla_toolbox module were returning stdout
and stderr as a single output object. This could break JSON parsing if
any data was present in stderr, for example warnings such as:

    [WARNING]: Collection ansible.posix does not support Ansible version 2.14.17

Fix by using demux=True to separate the two streams. The stderr content
is logged as it could be useful for troubleshooting or catching
deprecation notices.

Change-Id: Iad0476d4511f28c837794352c9a3e2f47113d9a1
Closes-Bug: #2080544