lava_dispatcher: RetryAction use last exception class for final exception
requested to merge igo95862/lava:collabora/staging-lava-dispatcher-mirror-timeout-exception-to-last-exception-class into collabora/staging
For example, if last try raised InfrastructureError the old code would convert it to JobError which could have undesired side effects. (like canceling health checks)
The new code will raise the same exception class as the last exception caught during last try.