Fix the system property name in a comment

The system property to enable jdwp should be
persist.debug.dalvik.vm.jdwp.enabled and not
persist.debuggable.dalvik.vm.jdwp.enabled

Bug: 277161682
Test: A change to comment
Change-Id: Ib8e509b5362d389239094eee575336a5a65d56d9