FixedDomainConfigurationCountJobGenerator is not thread-safe

After fixing NAS-2069, revision 2618 (part of NAS-2169 fix) removed synchronized statement from generateJobs in FixedDomainConfigurationCountJobGenerator. But the job generation methods make use of an instance boolean member, so the class is not thread safe anymore.

In production we had a broad harvest job generation that got intertwined with a focused job generation, resulting in all subsequent broad jobs having the focused configuration count instead of the broad one.