PLT-6240: Remove own pinned post from RHS when removed from channel (#6098)

Dispatch REMOVE_POST event after successfully initiating delete post,
others get informed by websocket event and will mark the msg as deleted
but not delete from RHS.

webapp/stores/search_store.jsx

@@ -133,6 +133,19 @@ class SearchStoreClass extends EventEmitter {
             });
         }
     }
+
+    removePost(post) {
+        const results = this.getSearchResults();
+        if (results == null) {
+            return;
+        }
+
+        const index = results.order.indexOf(post.id);
+        if (index > -1) {
+            delete results.posts[post.id];
+            results.order.splice(index, 1);
+        }
+    }
 }
 
 var SearchStore = new SearchStoreClass();
@@ -171,6 +184,10 @@ SearchStore.dispatchToken = AppDispatcher.register((payload) => {
         SearchStore.togglePinPost(action.reaction, false);
         SearchStore.emitSearchChange();
         break;
+    case ActionTypes.REMOVE_POST:
+        SearchStore.removePost(action.post);
+        SearchStore.emitSearchChange();
+        break;
     default:
     }
 });