Make mx-puppet-* bridges not log to files

We log everything in systemd/journald for every service already,
so there's no need for double-logging, bridges rotating log files
manually and other such nonsense.

roles/matrix-bridge-mx-puppet-slack/templates/config.yaml.j2

@@ -80,20 +80,4 @@ logging:
   lineDateFormat: MMM-D HH:mm:ss.SSS
   # Logging files
   # Log files are rotated daily by default
-  files:
-    # Log file path
-    - file: "/data/bridge.log"
-      # Log level for this file
-      # Allowed values starting with most verbose:
-      # silly, debug, verbose, info, warn, error
-      level: info
-      # Date and time formatting
-      datePattern: YYYY-MM-DD
-      # Maximum number of logs to keep.
-      # This can be a number of files or number of days.
-      # If using days, add 'd' as a suffix
-      maxFiles: 14d
-      # Maximum size of the file after which it will rotate. This can be a
-      # number of bytes, or units of kb, mb, and gb. If using the units, add
-      # 'k', 'm', or 'g' as the suffix
-      maxSize: 50m
+  files: []