Move vndk apex to the vendor partition for in-development builds

We may now install VNDK apex on vendor partition safely as product
modules no longer requires vndk libs.

Bug: 299867815
Bug: 307214977
Test: lunch cf_x86_64_phone-trunk_staging-userdebug; m
Change-Id: Ibc2391c326a392644e251d2938adedbdf8b23630