Avoid IndexOutOfBoundsException when accessing RemoteCallbackList

This is not a deep copy so it's the same reference. It is possible a
IndexOutOfBoundsException may happen.

Bug: 29385425
Test: build. Manual, add log to check.
1. Local add code to regiser with user 10 and 11
2. Boot and try to add and remove user or run
3. Check the logs and no exception occurs

Change-Id: I0d0da1cbb391e32ea0876e84960f9c61c4a89dd4