Move `host_supported: false` down from the cc_defaults module.

art_artd_tests gets `host_supported: true` from art_gtest_defaults, so
it needs to be overridden directly in the leaf module.

Cherry-picked from ag/18909799.

Test: m art_artd_tests art_standalone_artd_tests
  on master-art
Bug: 177273468
Change-Id: Ie2e03354872a91fc9a926b2ba0ee477b4da17643
Merged-In: Ie2e03354872a91fc9a926b2ba0ee477b4da17643