Separate outputs of kolla_toolbox inner module

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.

Depends-On: https://review.opendev.org/c/openstack/kolla-ansible/+/929294

Change-Id: Iad0476d4511f28c837794352c9a3e2f47113d9a1
Closes-Bug: #2080544
(cherry picked from commit 5407662)

ansible/library/kolla_toolbox.py

@@ -181,7 +181,9 @@ def use_docker(module):
                        "ANSIBLE_LOAD_CALLBACK_PLUGINS": "True"}
         job = client.exec_create(kolla_toolbox, command_line,
                                  environment=environment, **kwargs)
-        json_output = client.exec_start(job)
+        json_output, error = client.exec_start(job, demux=True)
+        if error:
+            module.log(msg='Inner module stderr: %s' % error)
 
         try:
             output = json.loads(json_output)

releasenotes/notes/kolla-toolbox-demux-c5e8d27bc7214069.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes parsing of JSON output of inner modules called by ``kolla-toolbox``
+    when data was returned on standard error.
+    `LP#2080544 <https://launchpad.net/bugs/2080544>`__