Because of the large number of XFAILs TestThreadStates has decayed quite a bit. This commit does
the following:
- removes the "breakpoint list" expectations. Most tests have been failing on this, because the command output changed quite a while back. I remove it, because run_break_set_by_file_and_line already does a decent amount of checking
- fixup test_state_after_expression: this was calling the wrong function by mistake. As now the function actually tests something (which we know is broken), I needed to XFAIL it as well.
- replaces the sleep() with a proper wait-for-event functionality in parts which use async mode, to stabilize the one function that actually tests something.