Align the handling of no-mcc-mnc configs in vendor.xml with carrierconfig app am: 4fc47e4a1f am: 5dd439e18d am: 29bb818b42

Original change: https://android-review.googlesource.com/c/platform/tools/carrier_settings/+/1690689

Change-Id: I0943cd82e74a0bb84c33ad4a81664a5babee4d89