Truncate more ActionCable broadcast messages to 300 chars

Truncation to ActionCable logging was added way back in 2016, but here's
another location where the logging messages can get out of hand.

Author: dark-panda

actioncable/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Truncate broadcast logging messages.
+
+    *J Smith*
+
 *   OpenSSL constants are now used for Digest computations.
 
     *Dirkjan Bussink*

actioncable/lib/action_cable/server/broadcasting.rb

@@ -40,7 +40,7 @@ def initialize(server, broadcasting, coder:)
           end
 
           def broadcast(message)
-            server.logger.debug { "[ActionCable] Broadcasting to #{broadcasting}: #{message.inspect}" }
+            server.logger.debug { "[ActionCable] Broadcasting to #{broadcasting}: #{message.inspect.truncate(300)}" }
 
             payload = { broadcasting: broadcasting, message: message, coder: coder }
             ActiveSupport::Notifications.instrument("broadcast.action_cable", payload) do