e2e: fix switch lb rule test

[zhangzujian]

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

What type of this PR

• Tests

Which issue(s) this PR fixes:

Fixes occasional address conflict in switch lb rule e2e test.

WHAT

🤖 Generated by Copilot at d5a21ad

Remove pool annotation from statefulset test case. Use kube-ovn IPAM feature instead.

🤖 Generated by Copilot at d5a21ad

No more pool annotation
Statefulset pods use IPAM
Simpler and better

HOW

🤖 Generated by Copilot at d5a21ad

• Remove the pool annotation and the code that assigns random IPs to the statefulset pods (link). This simplifies the test case and aligns with the best practices of using kube-ovn IPAM feature to allocate IPs from the subnet. The file switch_lb_rule.go contains the test case for verifying the switch load balancing rule functionality.