CI: Improve readabiity of ansible output

Switching to the yaml callback plugin so that multiline strings are more
readable.

Change-Id: I92f60738813978e80f6dcf7fbd0a88bd3746f32f

Author: jovial

playbooks/kayobe-base/pre.yml

@@ -14,6 +14,9 @@
       # Add timing information to output
       callbacks_enabled = ansible.posix.profile_tasks
 
+      # Improve readability of ansible output.
+      stdout_callback = yaml
+
       [ssh_connection]
       # NOTE(wszusmki): Disable pipelining due to:
       # https://github.com/ansible/ansible/issues/81777
@@ -32,6 +35,9 @@
       # Add timing information to output
       callbacks_enabled = ansible.posix.profile_tasks
 
+      # Improve readability of ansible output.
+      stdout_callback = yaml
+
       [ssh_connection]
       # NOTE(wszusmki): Disable pipelining due to:
       # https://github.com/ansible/ansible/issues/81777