CI: Replace deprecated yaml callback plugin

[DEPRECATION WARNING]: community.general.yaml has been deprecated. The
plugin has been superseded by the option `result_format=yaml` in
callback plugin ansible.builtin.default from ansible-core 2.13 onwards.
This feature will be removed from community.general in version 12.0.0.

Change-Id: I173240e0c7b5559a1ef1eea95067bd9d6c390ab4
Signed-off-by: Pierre Riteau <pierre@stackhpc.com>

Author: priteau

playbooks/kayobe-base/pre.yml

@@ -15,7 +15,7 @@
       callbacks_enabled = ansible.posix.profile_tasks
 
       # Improve readability of ansible output.
-      stdout_callback = yaml
+      callback_result_format = yaml
 
       [ssh_connection]
       # NOTE(wszusmki): Disable pipelining due to:
@@ -36,7 +36,7 @@
       callbacks_enabled = ansible.posix.profile_tasks
 
       # Improve readability of ansible output.
-      stdout_callback = yaml
+      callback_result_format = yaml
 
       [ssh_connection]
       # NOTE(wszusmki): Disable pipelining due to: