Split/Refactor gcp manifests into separate kpt packages

[jlewi]

Right now we have one giant kpt package for the management and instance packages
https://github.com/kubeflow/manifests/tree/master/gcp/v2/management
https://github.com/kubeflow/manifests/tree/master/gcp/v2/cnrm

We should probably split these into separate kpt packages (e.g each one should have their own kpt file)

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Label	Probability
platform/gcp	0.97
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