RDDT: use brute force enabled knowhere tag (#32)

* use knowhere tag v2.6.15-3ae69f7ff5 with brute force search flag

RDDT: Group-by loop on proxy

RDDT: Group-by loop on proxy

RDDT: Fix Milvus unit tests

RDDT: Avoid materializing string views on group by

RDDT: add milvus slo latency buckets

RDDT: Add unittest BuildKit image and disable GitHub Actions

Introduce Dockerfile.unittest.buildkit to run `make unittest` (C++ and Go)
via internal CI without producing a runtime image. Disable auto-triggered
GitHub Actions workflows in this fork, including Claude Code review, so
they only run on workflow_dispatch.

Co-authored-by: Cursor <cursoragent@cursor.com>

Simplify

RDDT: Use roaring bitmap

RDDT: Use roaring bitmap