Release mediaplayer completely after destroying test call

Change-Id: Ibbe174a35858942d1f00b8c98dccadd215e54592
diff --git a/tests/src/com/android/server/telecom/testapps/TestConnectionService.java b/tests/src/com/android/server/telecom/testapps/TestConnectionService.java
index 2e01276..ce3af60 100644
--- a/tests/src/com/android/server/telecom/testapps/TestConnectionService.java
+++ b/tests/src/com/android/server/telecom/testapps/TestConnectionService.java
@@ -386,7 +386,7 @@
         if (mCalls.isEmpty() && mMediaPlayer != null && mMediaPlayer.isPlaying()) {
             mMediaPlayer.stop();
             mMediaPlayer.release();
-            mMediaPlayer = createMediaPlayer();
+            mMediaPlayer = null;
         }
 
         updateConferenceable();