Arbitrum integration: optimize l1 hotshot commitment fetcher

We can remove the redundant block height check because we are only fetching one commitment:
`contractBlockHeight, err := h.HotShot.HotshotCaller.BlockHeight(nil)`

Search the Rust codebase for HotShot.HotshotCaller.BlockHeight and inspect the L1 HotShot commitment fetcher around that call. Confirm that only one commitment is fetched, remove the redundant block-height check, and run the relevant existing tests if you find them; done means the fetcher still retrieves the commitment without that check.

Written by the indexing model from the issue text.