docs: configure or disable Kube-OVN pinger external probes on ACP 4.4

[zhangzujian]

Summary

• state explicitly that ACP 4.4 disables the Kube-OVN pinger external address and DNS probes by default
• explain how to investigate public DNS queries or ICMP traffic found during upgrades and traffic audits
• document how users can keep either probe disabled with an empty field or enable it with an approved internal target
• include recognizable historical public targets plus rollout, CoreDNS, and audit verification steps

Validation

• parsed the article front matter as YAML
• verified Markdown table widths and balanced code fences
• ran git diff --check
• ran helm unittest chart -f tests/pinger_test.yaml on chart-kube-ovn release-4.4: 2 tests passed
• GitHub Actions site builds passed for the first two revisions; the corrected revision will rerun it

References

• ACP-54755
• Kube-OVN chart MR !39 and !40: expose the fields
• Kube-OVN chart MR !41 and !42: make empty values disable the probes