fix: message_type inconsistency across message end points (#10108)

The `before_type_cast` method sometimes returns a string for
`message_type`, creating inconsistencies in different payloads. This
pull request will remove all `before_type_cast` usage and replace it
with `to_i` methods.

app/models/message.rb

@@ -137,7 +137,7 @@ class Message < ApplicationRecord
   def push_event_data
     data = attributes.symbolize_keys.merge(
       created_at: created_at.to_i,
-      message_type: message_type_before_type_cast,
+      message_type: message_type.to_i,
       conversation_id: conversation.display_id,
       conversation: conversation_push_event_data
     )