move ipam.subnet.mutex to caller

[hongzhen-ma]

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

What type of this PR

• Bug fixes

Which issue(s) this PR fixes:

Fixes #2570

[github-actions]

• The commit message should provide more context about the changes made in the patch.
• In the GetPodAddress function of subnet.go, the mutex is removed from the function and moved to the caller. However, the defer subnet.mutex.RUnlock() statement is still inside the function. This will cause a deadlock as the mutex will never be unlocked. The defer statement should also be moved to the caller.

[github-actions]

• The commit message should provide more context about the changes made in the patch.
• In the GetPodAddress function of subnet.go, the mutex is removed. This might cause race conditions if multiple goroutines try to access the same subnet at the same time. It's better to keep the mutex and move it to the caller function (GetPodAddress in ipam.go).

[hongzhen-ma]

已回合 release-1.11 release-1.10 和 release-1.9 分支