netem experiments don't support ipv6

[lernett]

netem experiments (such as pod latency) don't actually support ipv6

tc requires "protocol ipv6" to work with ipv6 addresses (https://man7.org/linux/man-pages/man8/tc-u32.8.html), but current implementation always sets "protocol ip"

litmus-go/chaoslib/litmus/network-chaos/helper/netem.go

Line 278 in ed49413

tc := fmt.Sprintf("sudo nsenter --net=%s tc filter add dev %v protocol ip parent 1:0 prio 3 u32 %s flowid 1:3", target.NetworkNsPath, netInterface, filter)

while ipv6 matching is used in the filter

litmus-go/chaoslib/litmus/network-chaos/helper/netem.go

Line 258 in ed49413

if isIPV6 {

if isIPV6 {
	filter = fmt.Sprintf("match ip6 dst %v", ip)
}

So instead of something like

nsenter -t 205408 -n tc filter add dev eth0 protocol ipv6 parent 1:0 prio 3 \
  u32 match ip6 dst 2001:db8:1:1::a:1/128 flowid 1:3

we get

nsenter -t 205408 -n tc filter add dev eth0 protocol ip parent 1:0 prio 3 \
  u32 match ip6 dst 2001:db8:1:1::a:1/128 flowid 1:3

and it doesn't work