increase maxCand for candidates with overlap hits

[slava77]

In presence of overlapping module hits we create candidates that are essentially identical and each of them roughly follows the same path in the following layer combinatorics.
IIUC, CKF does not branch in this case and simply adds both hits on one candidate.

This reduces the combinatorial coverage for mkFit.
I'm proposing to dynamically increase maxcand for comb candidates with overlapping hits (perhaps provisional on relatively similar picked up hit chi2).

@osschar @mmasciov we discussed this in 2022.12.07 meeting