Add "SHARED_LOADBALANCER_VIP" to internal addresses

[TortillaZHawaii]

When creating multiple internal forwarding rules for one address we need to use the address with .Purpose = "SHARED_LOADBALANCER_VIP". Otherwise we will receive an Error syncing load balancer: googleapi: Error 409: IP_IN_USE_BY_ANOTHER_RESOURCE - IP '10.164.0.18' is already being used by another resource .

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @TortillaZHawaii. Thanks for your PR.

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[TortillaZHawaii]

It looks like it is an issue for existing IP addresses. If an address was reserved before this change trying to reserve it again with .Purpose = "SHARED_LOADBALANCER_VIP" will lead to an error:

[manager.go:226] "Address reserve error" logger="Other controllers.L4Controller.L4Handler.AddressManager" serviceKey="default/hello-service" syncId=1608326150 err="googleapi: Error 409: IP_IN_USE_BY_ANOTHER_RESOURCE - IP '10.164.0.13' is already being used by another resource."

Not sure how to resolve it without traffic interruption

[mmamczur]

/ok-to-test