IAE: Service not registered: com.android.server.AccessibilityManagerService

bug:3331645

1. Let the binder the AccessibilityManagerService has obtained while connecting
   to an accessibility services be garbage collected since when binding we will
   will get in the on #onServiceConnected callback and it can be potentially
   another instance.

Change-Id: I87aa5e5f741e2e54c72d3d0d396ac00eda5aeb5c