Proto: classification of Wrong_slot_used_for_consensus_operation error

The classification of the Wrong_slot_used_for_consensus_operation error has been changed to Branch because it is possible for a previously valid operation to trigger this error during reclassification on a new head. This could lead to the unwarranted kicking of a peer if this error were Permanent.

The classification of this error should be set back to Permanent once the mempool checks the slot normalization more consistently across all levels.