Expand call forwarding logging.

Cleaned up logging code surrounding call forwarding indication changes.
Diagnosing failures to update the CFI indicator was not possible due
to missing logging.

Test: Manually togged CFI to confirm log messages.
Bug: 65760595
Merged-In: I4d06c842c3d21304e1df719a6d37085781f22e21
Change-Id: I94d546486a08547d0b1958708884b5e1725e322d