Filter paramiko messages in log config

Update the default server log config so that only messages at
CRITICAL or above from the paramiko.transport logger are logged.
Similarly, only log keystoneauth at WARNING.  Both of these are
fairly chatty on the zuul-launcher.  This matches the current
settings in OpenDev.

Change-Id: I5cfdefac15b630e5846571e2bfd54efb65804356
Depends-On: https://review.opendev.org/977169

zuul/ansible/logconfig.py

@@ -119,6 +119,14 @@ _DEFAULT_SERVER_LOGGING_CONFIG = {
             'handlers': ['console'],
             'level': 'WARN',
         },
+        'paramiko.transport': {
+            'handlers': ['console'],
+            'level': 'CRITICAL',
+        },
+        'keystoneauth': {
+            'handlers': ['console'],
+            'level': 'WARNING',
+        },
     },
     'root': {'handlers': []},
 }