The test libraries have been inconsistently compiled depending on the enablePreview settings in the test that first compiles the test library class.

Jtreg has been enhanced to provide configure the enablePreview setting for each test library root. CODETOOLS-7903775: Add LIBRARY.properties

Since Valhalla tests need to be run both with and without --enable-preview, it is should be the case that the test libraries that do not depend on preview features be compiled without enable preview.