[Backport 2.x] Add model version to model metadata and change model metadata reads to be from cluster metadata

[ryanbogan]

Description

Backport of https://github.com/opensearch-project/k-NN/pull/2005, including fix from https://github.com/opensearch-project/k-NN/pull/2062

Check List

• [x] New functionality includes testing.
• [x] New functionality has been documented.
• [x] API changes companion pull request created.
• [x] Commits are signed per the DCO using --signoff.
• [x] Public documentation issue/PR created.

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[navneet1v]

@ryanbogan the tests are still failing.