Do not block deletion if NEG status is empty

[fdfzcq]

Fix a bug where an empty cloud.google.com/neg-status blocks deletion of the service resource.

To reproduce the bug:

• create a new service.yaml with autoneg annotations pointing to an invalid port
• try removing the service resource manually, the deletion hangs
• the deletion completes if we patch the resource with finalizers:null

[google-cla]

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[rosmo]

Would love to merge this. @fdfzcq I think you need to put in your corp email to Github for the CLA check to work.

[fdfzcq]

@rosmo I'm looking into failed tests

[rosmo]

@fdfzcq Good to merge?

[fdfzcq]

@rosmo I think we are good to go! Can you make a new release when this is merged? Thank you!

[rosmo]

Made 0.9.9 release :)

[fdfzcq]

@rosmo thank you!