Add time printout when scheduler starts/ends timing events
Including this for further debugging of the HLT2 nightlies.
The hlt2 reco
and hlt2 brunelesque
nightlies still report quite different throughputs which is in the process of being investigated.
This MR will provide some more information to track down the cause.
the wider we can include this in the nightlies the better.
But since we just again saw the problem in lhcb-head
maybe we can at least add that label?