deal with failed probes when all processing jobs fail. Fix #8792

[belforte]

I am still not sure that this will not break some existing functionality

[cmsdmwmbot]

Jenkins results:

• Python3 Pylint check: succeeded
  • 7 comments to review
• Pycodestyle check: succeeded
  • 19 comments to review

Details at https://cmssdt.cern.ch/dmwm-jenkins/view/All/job/DMWM-CRABServer-PR-test/2280/artifact/artifacts/PullRequestReport.html

[belforte]

after sleeping on it and further thinking, I believe that this is good