Update ro.vendor.api_level for non-GRF devices

Non-GRF devices must read only the `ro.product.first_api_level` but
not the vendor build version because `ro.product.first_api_level` is
always less than or equal to `ro.vendor.build.version.sdk` for
non-GRF devices.

Bug: 218610653
Test: getprop ro.vendor.api_level
Change-Id: Ib98c33ae052daa949208c43bd441f98cf442da49