More verbose JiraService error logs
What does this MR do?
We are trying to solve a problem with JIRA #195794 (closed) but It's been very difficult so far because the error logs are clueless in self-hosted installations and in our Kibana logs.
This will log the exception class and the backtrace. I've also refactored a little bit some specs in a separate commit.
Closes #198411 (closed)