Fix delay when navigating to a cluster

- `loadCluster` --> `await dispatch('cluster/unsubscribe');` --> cleanupTasks.push(waitFor(() => !this.$workers[getters.storeName], 'Worker is destroyed'));
- the waitFor was not immediately resolved, so waited the default 500ms before checking again
- for some reason we're now not in the immediate world so wait the 500ms
- resolution is to reduce the delay in waitFor to 50ms

Author: richard-cox

shell/plugins/steve/subscribe.js

@@ -470,7 +470,7 @@ const sharedActions = {
 
     if (worker) {
       worker.postMessage({ destroyWorker: true }); // we're only passing the boolean here because the key needs to be something truthy to ensure it's passed on the object.
-      cleanupTasks.push(waitFor(() => !this.$workers[getters.storeName], 'Worker is destroyed'));
+      cleanupTasks.push(waitFor(() => !this.$workers[getters.storeName], 'Worker is destroyed', 3000000, 50));
     }
 
     if ( socket ) {