Examples: remove application name added to Android manifests.

To build with Flutter 2.2.

Author: greenrobot-team

objectbox/example/flutter/objectbox_demo/android/app/src/main/AndroidManifest.xml

@@ -2,7 +2,6 @@
     package="com.example.objectbox_demo">
    <application
         android:label="objectbox_demo"
-        android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"

objectbox/example/flutter/objectbox_demo_relations/android/app/src/main/AndroidManifest.xml

@@ -2,7 +2,6 @@
     package="com.example.objectbox_demo_relations">
    <application
         android:label="objectbox_demo_relations"
-        android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"

objectbox/example/flutter/objectbox_demo_sync/android/app/src/main/AndroidManifest.xml

@@ -2,7 +2,6 @@
     package="com.example.objectbox_demo_sync">
    <application
         android:label="objectbox_demo_sync"
-        android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"