Ensure we only bind to CallScreeningService once.

Where the default dialer also fills the caller ID and spam role, ensure
that we only bind to the underlying CallScreeningService once.

Bug: 140950071
Test: Manual test by setting default dialer as the caller id and spam
role filler; verify we only bind once in Telecom logs.
Test: Added new unit test to ensure Callscreeningservicecontroller only
binds a single time.

Change-Id: Ib8c46b409ab69f43e04ba882c97545d7028ff764