hwbcc-rust: skip tests in trusty vms

Certain tests were written assuming a specific hard-coded emulator key
and degenerate certs. Don't set the generic-arm-unittest feature when
trusty is running as a vm guest.

Also introduce a separate feature for trusty as a vm guest so that we
can skip tests for unsupported features like TestMode and
ns_deprivilege.

Bug: 405148817
Test: atest TrustyVmUnitTests
Change-Id: Iecc0033bb0d2a92e8de06be001b8656a2b314707
2 files changed