Simplex Sending out Unnecessary Replication Requests

Our current replication logic keeps track of a `highestSequenceObserved`. This gets initially set when we receive a `finalization` from a future round, but can be updated during the replication process if a node sends us a `LatestRound` with a higher sequence.

Setting `LatestRound` see [here](https://github.com/ava-labs/Simplex/blob/39740e5dddf56b2466e44ca3ae4afc6fac110a23/epoch.go#L2464)
Updating `highestSequenceObserved` with `LatestRound` see [here](https://github.com/ava-labs/Simplex/blob/39740e5dddf56b2466e44ca3ae4afc6fac110a23/epoch.go#L2617-L2618)

We assume `highestSequenceObserved` keep tracks of the latest `Finalized` sequence and will therefore re-send replication requests until we get a finalization for that sequence. However, it's possible that we have actually caught up since the `LatestRound` sent prior was a notarization.