Remove unneccesary FCM manifest attribute.

`firebase_analytics_collection_enabled` is used for temporarily
enabling/disabling analytics.

We already use `firebase_analytics_collection_deactivated`, which is
used for permanently disabling analytics.

AndroidManifest.xml

@@ -109,7 +109,6 @@
     <meta-data android:name="firebase_analytics_collection_deactivated" android:value="true" />
     <meta-data android:name="google_analytics_adid_collection_enabled" android:value="false" />
     <meta-data android:name="firebase_messaging_auto_init_enabled" android:value="false" />
-    <meta-data android:name="firebase_analytics_collection_enabled" android:value="false" />
 
     <activity android:name="org.thoughtcrime.securesms.WebRtcCallActivity"
               android:excludeFromRecents="true"