Handle Context#unbindService exception

Unbinding a service for a user that is already stopped will throw
a java.lang.IllegalArgumentException: Service not registered:
com.android.server.storage.StorageUserConnection$ActiveConnection$1@370cd2c

We now handle this to avoid crashing the system

Test: m
Bug: 152299941
Change-Id: I8a76f760f67716f3cafc320a52bdcdad7bdc5d23