oeqa/selftest/distrodata: Fix up rust maintainer testing

oeqa/selftest/distrodata: Fix up rust maintainer testing

Since the target rust recipe is skipped but the native variant is not,
this confuses the test. Add rust to the list of special cases to avoid
test failures as the current code can't handle the skip.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>