Fix run_tests to not mask bash8 errors

The addition of the crazy-refs check masked the bash8 exit code.  So add
the same pass/fail handling from exercise.sh to provide a neat summary at
the end of the run.

Change-Id: I169eb90c619a114cf8584bee70b7dcda67769dc5
Skip child process kills in stack.sh exit trap

Logs are still being cut off in certain circumstances, almost certainly
because the awk process handling the output for verbose logging to a file
dies/is killed early.

Don't kill child processes in the EXIT trap function in this specific case.

Change-Id: I89600b61d59f87e93ff959710d0169e49d2c9845
Merge "Fix run_tests to not mask bash8 errors"
Merge "Skip child process kills in stack.sh exit trap"
Merge branch 'master' of https://github.com/openstack-dev/devstack