Merge branch 'alin/MR-427-drop-after_split-assert' into 'master'

fix: [MR-427] Drop redundant assert in `after_split()`

`ReplicatedState::consensus_queue` is empty at all round boundaries. So we
can safely assert this fact in `ReplicatedState::split()`.

But `ReplicatedState::after_split()` runs on top of the mutable tip; and while
it is called as early as possible, before anything is pushed onto
`consensus_queue`, making the same assertion again is either redundant (if
nothing changed) or dangerous (if anything was enqueued at the beginning of the
round). 

See merge request dfinity-lab/public/ic!12675

Author: alin-at-dfinity

rs/replicated_state/src/replicated_state.rs

@@ -926,9 +926,6 @@ impl ReplicatedState {
             .split_from
             .expect("Not a state resulting from a subnet split");
 
-        // Consensus queue is always empty at the end of the round.
-        assert!(consensus_queue.is_empty());
-
         // Adjust `CanisterQueues::(local|remote)_subnet_input_schedule` based on which
         // canisters are present in `canister_states`.
         let local_canister_ids = canister_states.keys().cloned().collect::<Vec<_>>();