Enable negative-E thinning of neutral FlowElement collection
As discussed in !38816 (merged), we want to be removing negative energy FlowElements from the collection written to AOD. This is already done for the old-style PFOs and was simply overlooked earlier when FlowElements were added earlier. This configures the thinning tool do thin the FlowElement container in addition to the older PFO one. The result should be a somewhat decreased event size for the JetETMissNeutralFlowElements collection (it looked like a saving on the order of 10kb/evt on the handful of dijet events I used for local testing).
Edited by William Keaton Balunas