Mempool behavior should not be user-specific.
Checking that txfee is acceptable should be
the responsibility of the wallet or client, not
the mempool.
This is a backport of core#19339 [3/3]
https://github.com/bitcoin/bitcoin/pull/19339/commits/b048b275d9711f70847afaea5450f17a0f7e673a
Depends on D10465