Avoid rendering the tree twice in a row

The callee already renders the tree if necessary, so despite the documentation
of the function, doing it again on the caller side is unnecessary.

src/key_press.c

@@ -31,9 +31,5 @@ void handle_key_press(xcb_key_press_event_t *event) {
         return;
 
     CommandResult *result = run_binding(bind, NULL);
-
-    if (result->needs_tree_render)
-        tree_render();
-
     command_result_free(result);
 }