Wait for at least 60 seconds for 0.3.5 and earlier to bootstrap

The basic-min network is still a bit unstable, but only for 0.3.5. (And it's much more unrealiable on macOS than Linux.)

It seems like 0.3.5 needs around 60 seconds to bootstrap and sync descriptors. Later versions have microdescriptor download fixes, and they can bootstrap and verify in just over 20 seconds on basic-min.

So let's make the minimum wait time 70 seconds (3 consensuses), if any nodes in the network are running 0.3.5 (or earlier).