let the actor module ignore the failed jobs if the call fails to wmstats

[sharad1126]

Impact of the bug
the actor module fails

Describe the bug
https://cms-unified.web.cern.ch/cms-unified/logs/actor/2020-05-07_11:15:09.log
If the call to wmstats for getting the failedjobs returns None or an empty json, then the actor module fails. We have this only to change the ACDC priority. My understanding is that, this is not an important component that should fail the actor module. Hence, we should either do multiple-retries or keep a check if the json returned is empty or something, we should just double the priority like before we implemented this.

How to reproduce it
https://cms-unified.web.cern.ch/cms-unified/logs/actor/2020-05-07_11:15:09.log

Expected behavior
Module shouldn't fail because of not getting the number of failed jobs. Let's say we should fail it gracefully and just double the priority as in we do for normal cases.

Additional context and error message
@z4027163 I think this is an important patch and should be made asap. @jenimal fyi

[sharad1126]

another log to support the point: https://cms-unified.web.cern.ch/cms-unified/logs/actor/2020-05-07_11:31:01.log