Revert "GA for gVNIC support (#4511)"

[modular-magician]

This reverts commit d63a4a8ff2b7d89e5a66739d1d3b629c8437074e.

GoogleCloudPlatform/magic-modules#4511 works fine for Compute Instances, but there is issues with Instance Templates. Reverting for now.

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Derived from GoogleCloudPlatform/magic-modules#4519