pinger: use fully qualified domain name

[zhangzujian]

• Make sure you have followed Kube-OVN Code Style.

What type of this PR

Examples of user facing changes:

• Features
• Bug fixes
• Docs
• Tests

Which issue(s) this PR fixes:

Avoid DNS requests for invalid domains such as alauda.cn.svc.cluster.local.

WHAT

🤖 Generated by Copilot at 1583422

This pull request updates the external-dns argument values for the pinger component in different network configurations. It uses google.com. as a more reliable external DNS server and adds dots at the end of the domain names to improve DNS resolution. The affected files are ./charts/values.yaml, yamls/kube-ovn-dual-stack.yaml, yamls/kube-ovn-ipv6.yaml, and yamls/kube-ovn.yaml.

🤖 Generated by Copilot at 1583422

Sing, O Muse, of the cunning coder who changed the pinger's domain
From alauda.cn to google.com., a more reliable name
As swift as Hermes, he altered the arguments for dual-stack and IPv6
And added a dot for IPv4, like a Cyclops' single eye

HOW

🤖 Generated by Copilot at 1583422

• Add a dot at the end of the external DNS domain name for the pinger component to improve DNS resolution (link, link, link, link)
• Replace the external DNS domain name from alauda.cn to google.com. for the dual-stack and IPv6 configurations to use a more reliable and widely available DNS server (link, link)