Investigate notarizations beyond the limit of defaultMaxRoundWindow

[yacovm]

Currently, we hold all rounds in memory and we get rid of a round only whenever we commit its finalization certificate and the round is too far in the past.

When we collect notarizations, we advance to higher rounds, but we may not collect finalizations.

We should investigate the behavior of the epoch when it receives more consecutive notarizations than defaultMaxRoundWindow, and see whether it's still possible to finalize blocks only after it has received too many notarizations.