[net processing] Remove mempool argument from AlreadyHaveBlock()
Summary:
Partial backport of core#19610:
https://github.com/bitcoin/bitcoin/pull/19610/commits/430e183b89d00b4148f0b77a6fcacca2cd948202
Depends on D9502.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D9503