TestingTorNetwork should not set AssumeReachable 1
For S55 we are trying to get self-tests and remote-tests working with IPv6. To make sure we've succeed, we need to try them with Chutney. But to try them with chutney, we need them to be enabled.
With legacy/trac#33583 (moved) we removed AssumeReachable from the chutney configurations. But that didn't actually have any effect, since
AssumeReachable 1 is implicit in