We observed some test failures like for example 1 where this assertion
was failing because message is `Error reading SSH protocol banner`.

Because the purpose of this specific test is to check that log rotation
of ban log work as expected and because we test more thoroughly the
ban itself in TestBan.test_client_are_banned_after_5_wrong_passwords, we
can simplify this test by just asserting that connection was refused, by
expecting a general exception. We don't care about the details of the
exception here.

After a ban, the first connection attemps seem to always be refused with
"Connection reset by peer" and that's why we did not observed failures
with TestBan.test_client_are_banned_after_5_wrong_passwords

[1]: https://nexedijs.erp5.net/#/test_result_module/20211208-1520AC26C/21