Historically, IptablesRulesTotal could have been intepreted as either
"the total number of iptables rules kube-proxy is responsible for" or
"the number of iptables rules kube-proxy rewrote on the last sync".
Post-MinimizeIPTablesRestore, these are very different things (and
IptablesRulesTotal unintentionally became the latter).
Fix IptablesRulesTotal (sync_proxy_rules_iptables_total) to be "the
total number of iptables rules kube-proxy is responsible for" and add
IptablesRulesLastSync (sync_proxy_rules_iptables_last) to be "the
number of iptables rules kube-proxy rewrote on the last sync".
68ed020b2a