RFR (T) 8241320: The ClassLoaderData::_is_unsafe_anonymous field is unused in the SA

[coleen.phillimore at oracle.com]

Summary: remove unused code that is changing in Hotspot for hidden classes.

Ran tier1-3 tests.  See bug for more details.

open webrev at http://cr.openjdk.java.net/~coleenp/2020/8241320.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8241320

Thanks,
Coleen