Support updating min_qps on vector search endpoints via PatchEndpoint

[janniklasrose]

Adds min_qps as an optional+computed field on databricks_vector_search_endpoint. Updates call PatchEndpoint when min_qps changes; reads the value back from ScalingInfo.RequestedMinQps on each read. Also marks scaling_info as read-only to avoid ambiguity. Includes a unit test for the update path.

Co-authored-by: Isaac

Changes

Tests

• make test run locally
• relevant change in docs/ folder
• covered with integration tests in internal/acceptance
• using Go SDK
• using TF Plugin Framework
• has entry in NEXT_CHANGELOG.md file

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• PR number: 5584
• Commit SHA: a375f0700573d48331ca759f957c0503a5b7292d

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