feat(flutter): 移除原生静态开屏

android/app/src/main/res/drawable-v31/launch_background.xml

@@ -1,7 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- Author: fruit.com.cn -->
-<!-- Android 12 already shows the icon in the system splash. This layer stays
-     the same color so the icon is not drawn a second time. -->
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
     <item android:drawable="@color/splash_background" />