Reapply "Allow "experimental" class to be always loadable."

This reverts commit e9a35312.
(original cl: I68e5356465a2e6c4ae053d406ef0740b77968685)

Bug: 292141694
Flag: TEST_ONLY
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh -r
Change-Id: I077d50add53836b32930339d8b6b28f065d0562b