Remove splash screen activity from sample app

Summary: The yoga splash screen that runs at the beginning of the app is unnecessary and can be removed for simplicty.

Reviewed By: emilsjolander

Differential Revision: D4571624

fbshipit-source-id: 3eb12f7c3447805f4546bd192df9670c5427572a

android/sample/AndroidManifest.xml

@@ -30,21 +30,16 @@
       >
 
     <activity
-        android:name=".SplashScreenActivity"
+        android:name=".MainActivity"
         android:exported="true"
-        android:theme="@style/AppFullScreenTheme"
         >
 
       <intent-filter>
         <action android:name="android.intent.action.MAIN"/>
         <category android:name="android.intent.category.LAUNCHER"/>
       </intent-filter>
-    </activity>
 
-    <activity
-        android:name=".MainActivity"
-        android:exported="false"
-        />
+    </activity>
 
   </application>