fix: Use last_activity_at instead of updated_at for sorting (#1281)

Co-authored-by: Akash Srivastava <akash.srivastava.1911@gmail.com>

app/models/message.rb

@@ -129,6 +129,7 @@ class Message < ApplicationRecord
   def execute_after_create_commit_callbacks
     # rails issue with order of active record callbacks being executed
     # https://github.com/rails/rails/issues/20911
+    set_conversation_activity
     dispatch_create_events
     send_reply
     execute_message_template_hooks
@@ -191,4 +192,10 @@ class Message < ApplicationRecord
   def validate_attachments_limit(_attachment)
     errors.add(attachments: 'exceeded maximum allowed') if attachments.size >= NUMBER_OF_PERMITTED_ATTACHMENTS
   end
+
+  def set_conversation_activity
+    # rubocop:disable Rails/SkipsModelValidations
+    conversation.update_columns(last_activity_at: created_at)
+    # rubocop:enable Rails/SkipsModelValidations
+  end
 end