Merge #10376: [tests] fix disconnect_ban intermittency

Summary:
3ba2c08 [tests] fix disconnect_ban intermittency (John Newbery)

Tree-SHA512: f4e1a88b4126ad5e1aa861a99f9b2589194a25610b5e18bcc196e7dccfa02491f0b9549fbb9f9a73776ed5ee2f6b8ade264b92ac378a25c1a92df4b0272487a7

Backport of Core PR10376
https://github.com/bitcoin/bitcoin/pull/10376/files

Test Plan: test_runner.py p2p_disconnect_ban

Reviewers: #bitcoin_abc, deadalnix, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D3362