Fix race when job filters are updated

Until now, job filters being added, modified, or deleted triggered
a scheduler run (`scheduleSomeJobs`) from the place where the filter
modification request is handled (Query.Server).

This could lead to a race:
If the config change containing the updated filters doesn't propagate
fast enough (it is asynchronous), `scheduleSomeJobs` will be triggered
with the old config.

This race only showed up in QAs with larger clusters.