TestLockPointValidity to txmempool

Summary:
This is a partial backport of core#22677 and core#23649
https://github.com/bitcoin/bitcoin/pull/22677/commits/1b3a11e126b258fba975ed7c452221608f2c5472
https://github.com/bitcoin/bitcoin/pull/23649/commits/ddd74ff65c471c5c25815ac0643d16ea0d51f58f

Depends on D12442

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12440