testing: what happens when server crashes and restarts

https://github.com/Rishabh04-02/Libreswan-Opportunistic-IPsec/issues/8

Note: east is clear-or-private, so what we expect:

road triggers OE to east.
east is 'crashed;
road has dpd triggers cleanup of OE
road triggers OE to east but it is still down, installs %pass shunt
east is started back up

but since east is in clear-or-private, it won't trigger OE and road
has a pass, so until shunt expires, no OE will happen and it all goes
in the clear.

A better test case would test with east also private-or-clear. That
would be a more real scenario. and should end in encrypted traffic
once east is back up
