Make testUpdateMccMncConfiguration more stable.

testUpdateMccMncConfiguration was relying on the output of
adb shell am get-config
in order to determine whether the MNC/MCC changes were applied correctly.
In addition to the test being unrealistic due to the fact that it was just
reading internal state from a shell command, it was also susceptible to
format changes in the "am get-config" command.

Refactoring the test to use the actual configuration API instead of a
shell command.

Test: Run CTS test to verify it passes.
Fixes: 227132285
Change-Id: Ia860e47c70f2cabccfc4fc2406cb5438d002bca2
1 file changed