Fix timeline streaming stopping for multiple sessions instead of one (m…

…astodon#17259)

* Fix timeline streaming stopping for multiple sessions instead of one

Fixes mastodon#17256.

In updating the code for a newer version of node-redis, mastodon#17183 also broke
redis subscription management when multiple streaming clients subscribe to the
same channel.

This commit restores the redis subscription management code.

* Let node-redis actually handle the subscriptions

streaming/index.js

@@ -254,9 +254,10 @@ const startWorker = async (workerId) => {
    * @param {string} channel
    * @param {SubscriptionListener} callback
    */
-  const unsubscribe = (channel) => {
+  const unsubscribe = (channel, callback) => {
+    log.silly(`Removing listener for ${channel}`);
 
-    redisSubscribeClient.unsubscribe(channel);
+    redisSubscribeClient.unsubscribe(channel, callback);
   };
 
   const FALSE_VALUES = [