Fix up android.core CTS tests.

Fix several wrongly configured tests that were either
looking for tests in the wrong jar (apache-harmony-tests
instead of core-tests) or using the wrong prefix.

Also, this change creates subsets of the harmony tests based
on subpackage names (java.net, java.io, java.nio etc.) instead
of the earlier harmony groupings.

(cherry picked from commit 7b857b92)

Change-Id: I5bca5bf53b4a14c88fd7a1e5685c07615c515adc