Update Dataproc WorkflowTemplate, rename REQUIRED_OVERRIDE

[modular-magician]

Changes the name of REQUIRED_OVERRIDE to CUSTOM_SCHEMA_VALUES as that makes a little more sense (it applies to more than required) and removes the ForceNew value since it wasn't hooked up anywhere.

This updates the Dataproc WorkflowTemplate resource, fixing the version field retyping that was otherwise blocking GoogleCloudPlatform/magic-modules#5197. I deprecated it- not sure if it's on the docket for 4.0.0, I haven't rolled it in yet (we already have enough to do)

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• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
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Release Note Template for Downstream PRs (will be copied)

dataproc: deprecated the `google_dataproc_workflow_template.version` field, as it wasn't actually useful. The field is used during updates, but updates aren't currently possible with the resource.

Derived from GoogleCloudPlatform/magic-modules#5249