Keep task stdout/stderr separate in result object

Combining stdout/stderr in the result can lead to problems when e.g.
the stdout of a task is used as an input for another task.

This is also different from the normal Ansible behavior and can be
surprising and hard to debug for users.

The new behavior is configurable and off by default to retain backward
compatibility.

Change-Id: Icaced970650913f9632a8db75a5970a38d3a6bc4
Co-Authored-By: James E. Blair <jim@acmegating.com>

playbooks/zuul-stream/functional.yaml

@@ -18,6 +18,7 @@
         ZUUL_CONSOLE_PORT: 19887
         ZUUL_JOB_LOG_CONFIG: "{{ ansible_user_dir}}/logging.json"
         ZUUL_JOBDIR: "{{ ansible_user_dir}}"
+        ZUUL_ANSIBLE_SPLIT_STREAMS: False
         PYTHONPATH: "{{ python_path }}"
       register: _success_output
 
@@ -59,6 +60,7 @@
       environment:
         ZUUL_JOB_LOG_CONFIG: "{{ ansible_user_dir}}/logging.json"
         ZUUL_JOBDIR: "{{ ansible_user_dir}}"
+        ZUUL_ANSIBLE_SPLIT_STREAMS: False
         PYTHONPATH: "{{ python_path }}"
       register: _success_output
 
@@ -101,6 +103,7 @@
         ZUUL_CONSOLE_PORT: 19887
         ZUUL_JOB_LOG_CONFIG: "{{ ansible_user_dir}}/logging.json"
         ZUUL_JOBDIR: "{{ ansible_user_dir}}"
+        ZUUL_ANSIBLE_SPLIT_STREAMS: False
         PYTHONPATH: "{{ python_path }}"
 
     - name: Save output