WiFiCallingSettings: don't start carrier app in onResume

onResume initialize UI before registering switch change listener.
So that listener is not invoked in UI initialization, but only real
switch change by user.

Bug: 33680334
Test: make
Test: manual - carrier app is not invoked in onResume
Change-Id: I7ca1eb1eab214b50c8de72946590c1ecb676d4df