The aliases are leftover from a previous MOVEONLY refactor - they are
unnecessary and removing them reduces the diff for splitting out mempool
Checks from PreChecks, making RBF variables MemPoolAccept-wide, etc.
This is a partial backport of core#23381
https://github.com/bitcoin/bitcoin/pull/23381/commits/9e910d8152e08d26ecce6592870adbe5dabd159e
Depends on D12352