DEV: Remove unused variable topic_tracking_state (#9915)

DEV: Remove unused variable topic_tracking_state (#9915)

diff --git a/app/models/topic_tracking_state.rb b/app/models/topic_tracking_state.rb
index 867961e..dcf1d60 100644
--- a/app/models/topic_tracking_state.rb
+++ b/app/models/topic_tracking_state.rb
@@ -9,7 +9,6 @@ class TopicTrackingState
 
   include ActiveModel::SerializerSupport
 
-  CHANNEL = "/user-tracking"
   UNREAD_MESSAGE_TYPE = "unread"
   LATEST_MESSAGE_TYPE = "latest"
   MUTED_MESSAGE_TYPE = "muted"

GitHub sha: 94cb5ab1

This commit appears in #9915 which was approved by eviltrout. It was merged by markvanlan.