Add TestVMDebug to prebuilt libjdwp skips

This test relies on functionality that is not implemented in the
prebuilt libjdwp.

Test: ./art/tools/run-prebuilt-libjdwp-tests.sh --mode=host
Bug: 62821960
Change-Id: I83dc8ce3ebbdaafbc8563a7496f662800424e92a