Implement scan_factor and max_candidates for query

[austin-denoble]

Problem

There are new parameters available on query for indexes with dedicated read nodes:

• scan_factor
• max_candidates

These were pulled into the 2025-10 API release and need to be added to the clients.

Solution

• Regenerate core off 2025-10 to pull in scan_factor and max_candidates.
• Add ScanFactor and MaxCandidates to QueryByVectorValuesRequest and QueryByVectorIdRequest, and wire through in IndexConnection.QueryByVectorValues and IndexConnection.QueryByVectorId.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Infrastructure change (CI configs, etc)
• Non-code change (docs, etc)
• None of the above: (explain here)

Test Plan

CI - unit and integration tests

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Note

Low Risk
Mostly additive, generated API surface changes plus simple request-field plumbing; low risk aside from potential client-side expectation changes around optional query parameters.

Overview
Adds two new optional query tuning parameters—scan_factor and max_candidates—to the 2025-10 generated gRPC and REST models (QueryRequest), including accessors/oneof metadata.

Extends IndexConnection query request types (QueryByVectorValuesRequest, QueryByVectorIdRequest) to accept these options and forwards them into the underlying db_data_grpc.QueryRequest, enabling DRN-specific recall/latency tuning without changing existing call patterns.

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