Fixed an issue that happened on the metachain when a block was received with a slight delay and some metachain nodes started building upon it but others were unable to sync. This resulted in a sort of network split and since we need 2/3+1 of all metachain nodes to give the signature on a proposed block, the metachain shard halted. The nodes that were unable to sync had a constraint check that allowed to add in the forkDetector component only blocks with a round greater or equal to the current round - finality constant so this "opportunity window" was missed by around 30 nodes. Those nodes, along the others that were offline resulted in an impossibility to add new blocks. This constraint was removed in this patch as to allow blocks with slightly less round index (but not less than final block round) to be added to the fork detector as to be able to easily recover from this situation.