Disable tethering profile when roaming

Some carriers require not using tethering APN when the device
is roaming. By returning false for TelephonyManager.isTetheringApnRequired(),
tethering service will automatically use the default network, which
supports internet, for tethering purposes.

Fix: 233002812
Test: atest DataProfileManagerTest + Basic testing
Merged-In: I175ee6616be0c0528c66f96934a4f2863761729c
Change-Id: I175ee6616be0c0528c66f96934a4f2863761729c