Make MCC-MNC logging pattern consistent with Android.

* It's ideal to convey both the network and SIM MCC-MNC.
* Although this isn't at the moment supported on this platform, we'll conform to the spec used on Android.
* See I10cd15cfb5a1625159e6ac2151938d3b24710e90 for the corresponding Android change.
* This change also accounts for the possibility of a missing MCC/MNC (e.g., no SIM cellular connection scenario).

Change-Id: I9dbc12201e03c1f2fe2b7fe3d30cfafaff801e2c
Merge "Make MCC-MNC logging pattern consistent with Android."