Reload allowed networks from db after restore content.

Since the allowed networks in db has changed after restoring the
enable 2g in allowed network type reasons, Added to reload based
on the allowed networks from db.

Bug: 314734614
Test: atest com.android.providers.telephony.TelephonyProviderTest
Test: tested manually with Pixel7, backup, factory reset and restored.
Test: basic telephony test call/data/networksetting
Change-Id: I04fea97d0f1cd17498d61821004c50806b357733