Separate test cleanup code in output and clean up ctdb restart code.

Separate test cleanup code in output and clean up ctdb restart code.

* ctdb_restart_when_done() now schedules a restart by setting an
  explicit variable that is respected in ctdb_test_exit(), rather than
  adding a restart to $ctdb_test_exit_hook.  This means that restarts
  are all done in one place.

* ctdb_test_exit() turns off "set -e" to make sure that all cleanup
  happens.

* ctdb_test_exit() now prints a clear message indicating where the
  test ends and the cleanup begins.  This message also includes the
  return code of the test.

* Add debug in cluster_is_healthy to try to capture information about
  unexpected unhealthiness when a test starts.

* Simplify simple/07_ctdb_process_exists.sh so that the exit code is
  generated more obviously.

* Remove redundant calls to ctdb_test_exit at the end of tests, since
  they're done automatically via a trap.  Also remove any preceding
  warnings of restarts or final hints about test success/failure.

* Allow multi-digit debug levels in simple/12_ctdb_getdebug.sh and
  simple/13_ctdb_setdebug.sh.

Signed-off-by: Martin Schwenke <martin@meltin.net>