Also use ThreadList::Dump() in empty checkpoint timeout.

After dumping runnable threading that haven't responded to the empty
checkpoint request, use ThreadList::Dump() to try to dump the other
threads, noting that it may get stuck, but it's the end of logging
anyway. This should help diagnose the timeout better as we would be
able to see more threads.

Bug: 33006388
Bug: 12687968
Test: test-art-host with CC.
Change-Id: I6936098949d53dbc74af11fd5d796e1524581468