Fix jet pd smear athena

During SUSYTools (ST) initialisation, the Jet PD Smear Uncertainty tool m_jetUncertaintiesPDSmearTool cannot be retrieved when it is not configured (and the default behaviour is to not configure the tool). The changes I have made are to simply remove the m_jetUncertaintiesPDSmearTool.retrieve() call for the case when the tool is not used. There is already a bool, m_jetUncertaintiesPDsmearing, which is used to control the configuration, so I made use of that to prevent the tool from being called if it has not been configured.