Khan-agent conntrack script regex misses many entries

Roughly 15% of all connection entries in the conntrack table do not match the regex and are therefore omitted from the exported metrics. Switching to one of the netfilter/conntrack go libraries should ensure each entry is accounted for.

Start by locating the Khan-agent conntrack script and reviewing the regex that parses connection entries. Compare its coverage with the netfilter/conntrack Go libraries, then verify that exported metrics account for every conntrack entry.

Written by the indexing model from the issue text.