commitment: evaluate `StateReader` implementation cleanup and replacement

Follow-up for #17531 based on comments there:

1. it should be possible to cleanup/simplify `LimitedHistoryStateReader` implementation according to [this comment](https://github.com/erigontech/erigon/pull/17531#discussion_r2443784004)
2. [another comment](https://github.com/erigontech/erigon/pull/17531#discussion_r2444497839) suggested to discuss if the new `commitmentdb.StateReader` abstraction should be replaced by existing `state.StateReader`

Start with issue #17531 and the two linked pull-request comments, then inspect the current LimitedHistoryStateReader, commitmentdb.StateReader, and state.StateReader implementations. The work is complete when the cleanup and replacement question has a documented decision and the relevant implementation changes are agreed.

Written by the indexing model from the issue text.