Revert "Android: Make the device watcher process terminate on shutdown"

This reverts commit e45e16d904.

Reason for revert: This one should look different in master

Change-Id: I4fbf3a9d046e5fe5a6a45d5ba93b685f5967498c
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/android/androidplugin.h

@@ -44,9 +44,6 @@ class AndroidPlugin final : public ExtensionSystem::IPlugin
 
     class AndroidPluginPrivate *d = nullptr;
 
-public:
-    ShutdownFlag aboutToShutdown() final;
-
 #ifdef WITH_TESTS
 private slots:
    void testAndroidSdkManagerProgressParser_data();