Do not disconnect peer for asking mempool if it has NO_BAN permission

Summary:
This is a partial backport of Core PR16248 : https://github.com/bitcoin/bitcoin/pull/16248/commits/ecd5cf7ea4c3644a30092100ffc399e30e193275

Depends on D5928

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, nakihito

Reviewed By: nakihito

Differential Revision: https://reviews.bitcoinabc.org/D5929