Fix Dex error due to conflicting packages (#4590)

Author: lfkellogg

firebase-appdistribution/src/androidTest/AndroidManifest.xml

@@ -14,7 +14,7 @@
 <!-- limitations under the License. -->
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.google.firebase.installations">
+    package="com.google.firebase.appdistribution.test">
 
     <application>
         <uses-library android:name="android.test.runner"/>