For non-REL branch, move VNDK APEX to /vendor partition so we don't need
to update vendor.img prebuilt everytime there is a change in the VNDK
libraries.
For REL branch, the API/ABI surfaces of VNDK libraries are frozen so
don't need to move to /vendor partition.
Bug: 140136207
Test: Build on REL and non-REL branch
Change-Id: Ibce24465b546c52bc447b4b28a474de2b4b53792
