Harmony: Use slow-debug for debug JDWP tests

Enable slow debug checks in the runtime for JDWP tests. Brings
the Makefile in line with art/tools/run-jdwp-tests.sh.

Bug: 35644369
Test: m
Change-Id: Icdbae9be840b221b0509db53412b697613859d7c
1 file changed