fix ovn lb gc

[zhangzujian]

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

What type of this PR

• Bug fixes
• Performance

Which issue(s) this PR fixes:

1. Fix ovn lb vip gc in dual-stack clusters;
2. Improve ovn lb gc performance.

WHAT

🤖 Generated by Copilot at 37b4454

This pull request enhances the garbage collection of load balancers and adds support for dual-stack services. It refactors the gcLoadBalancer function in pkg/controller/gc.go to use more efficient data structures and log more information. It also introduces a new helper function ServiceClusterIPs in pkg/util/k8s.go to get the cluster IPs of a service.

🤖 Generated by Copilot at 37b4454

Sing, O Muse, of the skillful coder who devised
A clever helper function, ServiceClusterIPs, to slice
The cluster IPs of services, whether one or two or none,
And handle dual-stack cases, both of IPv4 and IPv6.

HOW

🤖 Generated by Copilot at 37b4454

• Import time package and record start time of gcLoadBalancer function (link, link)
• Refactor logic of collecting VIPs of services for load balancers using maps and sets, and use ServiceClusterIPs helper function to handle dual-stack services (link, link)
• Add log messages and simplify conditions for deleting VIPs from TCP, TCP session, UDP, and UDP session load balancers using ok idiom (link, link, link, link)
• Add log message to indicate elapsed time of gcLoadBalancer function (link)