Align time zone + other country detection logic

This commit contains several changes to simplify country detection logic
and make it consistent for time zone detection and other use cases:

1) Change Ie3ec6768ffe924dd0be3e91a64dac32dacebe50b had removed some of
   the behavior that had led to time zone detection country detection
   being handled separately, i.e. time zone detection never wanted to
   use the country derived from the SIM. Apparently it was causing
   problems for other usecases as well and was removed.
2) Change I17ad7cd7691e02d65714ca727b0e8c4def220e42 introduced handling
   for when the radio was off. This is logic that should probably also
   have been applied to the time zone detection country detection logic
   too but wasn't probably contributing to bug 227047106. Bug 227047106
   meant that a country code was passed to the time zone detection logic
   rather than it making a handleCountryUnknown() call.
3) The code that first tries to obtain the country from the operator
   numeric did not use the MCC+MNC country lookup code. This was
   probably an oversight.
4) The code that tries to obtain the country from the nearby cell towers
   would only consider the MCC+MNC combination for time zone detection
   purposes. This change switches to using the MCC+MNC lookup for all
   cases.

The MCC+MNC country code lookup in (3) and (4) only matches a small
number of combinations today (see telephonylookup.xml in
system/timezone for the special cases). When there no match is found
using the MCC+MNC combination, the code will fall back to using the MCC,
retaining the prior behavior in the majority of cases.

After these changes, the logic for country code detection for time zone
and for other purposes are more similar: the only difference remaining
is the MCC 001 (test cell) handling to keep various TA tests associated
with time zone detection working.

Test: atest ./tests/telephonytests/src/com/android/internal/telephony/LocaleTrackerTest.java
Bug: 227047106
Change-Id: I2e11747d2cbbc59591e1f6b63bec969144bfe6f9