Remove versioning for terraform docs

[shainaraskas]

Our terraform doc versions are 8+ versions behind, and nothing changes between versions (the docs are just a stub that redirects)

This PR flattens the terraform docs so we just have one version, and no versioning confusion for end users.

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When I preview this, I still see this index page that has links - not sure how this is generated/whether this can be previewed in this build

https://docs_bk_3007.docs-preview.app.elstc.co/guide/en/tpec/index.html

@elastic/docs-engineering is there any way I can preview this before it ships?

[github-actions]

A documentation preview will be available soon.

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[shainaraskas]

@elasticmachine run docs-build rebuild

[lcawl]

LGTM as long as we create redirects