The iptables and ipvs proxies have code to try to preserve certain
iptables counters when modifying chains via iptables-restore, but the
counters in question only actually exist for the built-in chains (eg
INPUT, FORWARD, PREROUTING, etc), which we never modify via
iptables-restore (and in fact, *can't* safely modify via
iptables-restore), so we are really just doing a lot of unnecessary
work to copy the constant string "[0:0]" over from iptables-save
output to iptables-restore input. So stop doing that.
Also fix a confused error message when iptables-save fails.