Don't unnecessarily reevaluate tethering provisioning

Registering for carrier config changes can deliver a sticky broadcast
and can cause Tethering to think something has changed and reevaluate
provisioning status, even though this has been checked before it
entered tethering mode alive state.

Additionally, move the provisioning_app{,no_ui} resources into the
TetheringConfiguration, if for no other reason than now we can log
it in .toString().

Test: as follows
    - built
    - flashed
    - booted
    - runtest frameworks-net passes
    - manual USB tethering toward WiFi works
Bug: 69565814
Change-Id: Ib8b2620ce44c55e5eb0afd3f00f3f5aa4fc8a593