misc updates to KF Model Registry tutorial

[tarilabs]

• add suggestions of commands to dry-run connection from Notebook, this for instance was a feedback emerged interacting with users in https://github.com/kubeflow/model-registry/issues/90#issuecomment-2143788711
• refresh versions, by pinning to the latest version (and not just main, per previous KF community leads request)
• to make the tutorial flow easier, align model-version used for the mnist example ML model

[google-oss-prow[bot]]

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