When running checks, we look to the existing problem check trackers and try to grab their ProblemCheck classes.
In some cases this is no longer in the problem check repository, e.g. when the check was part of a plugin that has been uninstalled.
In the case where the check was scheduled, this would lead to an error in one of the jobs
Doing the following renames:
Jobs::ProblemChecks → Jobs::RunProblemChecks
Jobs::ProblemCheck → Jobs::RunProblemCheck
This is to disambiguate the ProblemCheck class name, ease fuzzy finding, and avoid needing to use :: in a bunch of places.