Update ban-state in case of dirty-state during periodic sweep

Summary:
Ensure the UI is updated when we update the banlist by calling it ouside of the cs_setBanned lock.

This is a backport of Core PR11616

Test Plan:

make check

Reviewers: #bitcoin_abc, schancel

Reviewed By: #bitcoin_abc, schancel

Subscribers: schancel, teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1880