Add group configuration and auth validation

[mihaimitrea-db]

Summary

Adds the group_id / DATABRICKS_GROUP_ID configuration and defines how authentication methods without group-assumption support behave.

• Automatic authentication skips unsupported providers so the chain can continue.
• Explicitly selected unsupported providers return an actionable DatabricksException.
• Configuration values work through profiles, environment variables, and code.

This is PR 1 of 3. The next PR adds OAuth group-assumption behavior.

Testing

• DatabricksConfigTest
• UnsupportedGroupCredentialsProviderTest
• Spotless and repository push checks

NO_CHANGELOG=true

[github-actions]

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Trigger:
go/deco-tests-run/sdk-java

Inputs:

• PR number: 898
• Commit SHA: bb922453d67f3a00c8f6a1e87441ad02f17d4a11

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