[Question] CloudMessaging - data-message doesn't receive when app is killed

### [REQUIRED] Please fill in the following fields:

* Pre-built SDK from the [website](https://firebase.google.com/download/cpp) or open-source from this repo: pre-built SDK
* Firebase C++ SDK version: 11.1.0
* Main Firebase Components in concern: Cloud Messaging
* Other Firebase Components in use: _____
* Platform you are using the C++ SDK on: Linux
* Platform you are targeting: Android

### [REQUIRED] Please describe the question here:

Adding the firebase-cpp-sdk to an Android Qt application, we receive the data messages when the app is in the foreground or background.

but when the app removes from the recent list, data-messages wont receive anymore.

we also prepared a sample application to reproduce this issue: https://github.com/ramajd/QPushTest

is there any part missed in our implementation?

从链接的 QPushTest 示例应用开始，在以 Android 为目标的 Linux 开发环境中使用 Firebase C++ SDK 11.1.0 重现该行为。比较应用处于前台、后台以及从最近使用列表中移除时 data-message 的传递情况；完成的标准是确定缺失的消息是由实现还是 SDK 行为导致的。

由索引模型根据 Issue 内容生成。