fuzz: Remove useless GetUTXOStats fuzz case

Summary:

In the GetUTXOStats fuzz case, GetUTXOStats is always called with a
CCoinsViewCache. Which is guaranteed to throw a std::logic_error when
its ::Cursor() method is called on the first line of GetUTXOStats.

In the fuzz case, we basically catch this logic error and declare
victory if we caught it.

There is no point to fuzzing this deterministic logic.

Confirmed with IWYU that the node/coinstats.h #include is no longer
necessary.

includes: Remove rpc/util.h -> node/coinstats.h

(Not needed since D11157)

This is a partial backport of core#24410
https://github.com/bitcoin/bitcoin/pull/24410/commits/0848db9c35d9eae4d68cbdbef68c337656f3c906
https://github.com/bitcoin/bitcoin/pull/24410/commits/1352e410a5b84070279ff28399083cb3ab278593

Depends on D14669

Test Plan: ninja bitcoin-fuzzers

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14671