Port yuzu-emu/yuzu#4528: "common: Make use of [[nodiscard]] where applicable" (#5535)

Co-authored-by: LC <712067+lioncash@users.noreply.github.com>

src/common/detached_tasks.cpp

@@ -34,8 +34,7 @@ void DetachedTasks::AddTask(std::function<void()> task) {
         std::unique_lock lock{instance->mutex};
         --instance->count;
         std::notify_all_at_thread_exit(instance->cv, std::move(lock));
-    })
-        .detach();
+    }).detach();
 }
 
 } // namespace Common