Until now, caucase stack was re-generating a new key every time
software release was upgraded. That was not really a problem because
we were not using this certificate but since af7a0208 (ERP5: Test
balancer partition and use caucase certificate for balancer, 2020-11-04)
we are using caucase certificate for balancer.

Problem is that it was not possible to update old instances, since on
"very old" instances the original key was lost and also since in af7a0208
we switch to using CSR template, this also generated a new key, so updating
from "not so old" instances was not possible either.

Now we have an upgrade test that will confirm that our changes in ERP5 do
not prevent from updating old instances, so we ignore all our past mistakes
with certificate management in this software release and start over with a
new data dir.