Improve `append_or_delete_dup_sorted`

### Describe the feature

`append_or_delete_dup_sorted` is confusing. Try to refactor the code or add comments
https://github.com/op-rs/op-reth/blob/28f6b8d59f384201620fb9cb71c34d9a64d7055d/crates/optimism/trie/src/db/store.rs#L120

### Additional context

_No response_