AnalysisTop: Disable FFJetSmearingTool when running nominal-only

This is a work-around which disables the initialization of the FFJetSmearingTool for jet mass resolution uncertainties, when not running systematic uncertainties. Under normal circumstances, we don't have to resort to such actions, but this tool consumes significant amount of memory (~2GB). The issue with the tool is being followed-up with JetEtMiss experts.