Improve logging of time zone detection (2/2)

This commit improves logging of time zone detection to
reduce the amount of log spam to the persistent (size 15)
local log buffer.

This is intended as change 2 of 2: adding the filtering
of "uninteresting" entries.

Bug: 138187241
Test: atest com.android.internal.telephony.NitzStateMachineImplTest
Change-Id: Ibace6ed7eec992b4440e27f9d03a434178cc86a9