fix ip statistics in subnet status

[zhangzujian]

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

What type of this PR

• Bug fixes

Which issue(s) this PR fixes:

Fixes incorrect ip statistics in subnet status:

  v4availableIPrange:      10.16.0.2-10.16.0.3,10.16.0.5,10.16.0.7-10.16.0.16,10.16.0.18-10.16.0.20,10.16.0.23-10.16.255.254
  v4availableIPs:          65529
  v4usingIPrange:          10.16.0.4,10.16.0.6,10.16.0.17,10.16.0.21-10.16.0.22
  v4usingIPs:              4

During deleting a pod, kube-ovn-controller deletes the IP CR first and then releases the IP address. There is a chance that subnet status update is triggered by the IP CR deletion before the IP address is released.

This patch fixes the ip statistics by releasing the IP address before deleting the IP CR.

WHAT

🤖 Generated by Copilot at 6d17481

This pull request improves the IP address management for pods by avoiding duplicate or stale allocations. It modifies the pod.go file to release the pod's IP address only once and before assigning a new one.

🤖 Generated by Copilot at 6d17481

Oh we are the coders of the pod.go file
And we work on the logic of the IP address style
We release the old one before we assign the new
To prevent the conflicts and the leaks that ensue

HOW

🤖 Generated by Copilot at 6d17481

• Release the IP address of a pod if it is marked for deletion, before allocating a new one, to avoid IP address conflicts and leaks in handleAddUpdatePod (link)
• Remove the redundant call to release the IP address of a pod in handleDeletePod, since it is already done in handleAddUpdatePod (link)

[github-actions]

• The order of the newly added code in handleDeletePod function should be reviewed. It is recommended to release the IP address before getting the pod networks.
• The error handling mechanism in getPodKubeovnNets function should be improved. Currently, if an error occurs, it only logs the error and continues execution. This may lead to unexpected behavior and should be handled properly.
• The naming convention of variables can be improved for better readability. For example, podNets can be renamed to podNetworks.
• The syncVirtualPortsQueue.Add(podNet.Subnet.Name) line can be moved outside the for loop to improve performance. This will avoid adding the same subnet name multiple times to the queue.
• It is recommended to add comments to the code to explain the purpose of each function and variable. This will make it easier for other developers to understand the code and maintain it in the future.