Adding ECFG_3_3_2 for MDT studies

Jason Robert Veatchrequested to merge
jveatch/athena:21.2-ECFG into 21.2

This adds the ECFG_3_3_2 moment back into EnergyCorrelatorGeneralizedTool. This is necessary for the current MDT studies. If it is found to be unnecessary it will be removed.

Tagging @cdelitzs, @mswiatlo, @farooque, and @tnobe

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