MOVEONLY: remove single-use helper func CheckInputsAndUpdateCoins

Summary:
This is a backport of core#21357 [5/8]
https://github.com/bitcoin/bitcoin/pull/23157/commits/09d18916afb0ecae90700d4befd9d5dc52767970

Depends on D12170

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12171