`mempool::Request::TransactionWithDepsByMinedId` appears to be unused

[syszery]

During the review of #11095, it was pointed out that mempool::Request::TransactionWithDepsByMinedId and mempool::Response::TransactionWithDeps (both in zebra-node-services/src/mempool.rs) still have a handler in zebrad/src/components/mempool.rs, but there are no remaining senders.

Before opening a follow-up PR, I'd like to ask what the preferred direction is. Are these request/response variants intentionally being kept for planned functionality, or should they be removed? If they're intended to remain, would it make sense to document that?

[conradoplg]

We could remove them, but that would be a breaking change and we'd probably want to wait for other breaking changes to ship along. (We kinda missed the boat now since we're about to make a release that includes a major bump to zebra-node-services, but not big deal)