Remove unassignable_types from vdex.

These were used in case a class went from "verified-at-runtime" to
"verified". With go/nterp, we're re not going to handle this situation
and we should only record what types the verifier expects to be
assignable.

Test: test.py
Bug: 112676029
Change-Id: I6ffa61cef3aa767dfccadbdfdd5432e72e143ca3
7 files changed