Update Kube-router ACCEPT rule insertion and install script to clean rules before start

[rbrtbnfgl]

Proposed Changes

Updated Kube-router version to add the default ACCEPT iptables rules right after the latest kubernetes rules to fix setup where a firewall that adds DROP rules is enabled.
Updated install.sh script to clean the iptables rules before K3s start.

Types of Changes

Verification

Testing

Linked Issues

#7203 #7244 #7251

User-Facing Change

The embedded kube-router controller has been updated to fix a regression that caused traffic from pods to be blocked by any default drop/deny rules present on the host. Users should still confirm that any externally-managed firewall rules explicitly allow traffic to/from pod and service networks, but this returns the old behavior that was relied upon by some users.

Further Comments

[rbrtbnfgl]

It seems that opensuse-leap test doesn't like iptables on the install script.
Does it right to keep the command there or not?

[brandond]

I was a little concerned about that. I see that we already use them in the uninstall script, but expecting them to be present at install time is probably not reasonable. Maybe just add a check to see if iptables and ip6tables exist before calling them?

[rbrtbnfgl]

Can I merge it even if it fails during s390 build?

[brandond]

I would say yes, go for it.