Updating subnet of sts won't trigger handleDeletePod which result in failed to create new port

[chestack]

Expected Behavior

updates sts with a new subnet, old sts pods deleted and new pods created

Actual Behavior

error message for new pod "port already exists but in switch ***(old subnet)"

Steps to Reproduce the Problem

1. default vpc with two subnets: ovn-default and subnet1
2. create sts with ovn.kubernetes.io/logical_switch: ovn-default , pods running then update sts with new subnet subnet1
3. new pod hang in ContainerCreating status with error
   E0711 11:28:26.560505 8 ovn-nbctl.go:242] create port wangbo-sts-0.alcubierres failed: ovn-nbctl: wangbo-sts-0.alcubierres: port already exists but in switch ovn-default E0711 11:28:26.560548 8 pod.go:366] error syncing 'alcubierres/wangbo-sts-0': ovn-nbctl: wangbo-sts-0.alcubierres: port already exists but in switch ovn-default