add timeCutUpperLimit flag for topoclusters

introduce timeCutUpperLimit flag for topoclusters

Hello,

This MR is introducing a 'timeCutUpperLimit' flag for topoclusters, with a default value of 20, in order to avoid hardcoded numbers in several places (ATLPHYSVAL-825).
This cut could possibly be tuned in specific domains, like pi0 reconstruction for taus, but until then, it's better to have a central flag controlling this.
I also added the timing cut to the CA configuration for pi0 topoclustering for taus, which was missing.

Cheers,
Bertrand