Bulk score hnsw neighbor array

[leng25]

issue #15606

Refactor NeighborArray#isWorstNonDiverse to use bulkScore instead of score, enabling multiple nodes to be evaluated at a time when searching for the worst neighbor to remove.

This change follows the approach taken in #15607, though unlike that case, this function is called less frequently so the direct performance gains are modest and within margin of error.

The primary motivation is consistency, aligning both call sites to use bulkScore ensures this code automatically benefits from any future optimizations made to implementations of that function.

Benchmarks run using luceneutil knnPerfTest
on a ThinkPad T14 Gen 1 (Intel i5-10210U, 8 logical cores, 16GB RAM, Linux).
Dataset: Cohere v3 Wikipedia 1024d, 50K docs, dot_product metric,
maxConn=64, beamWidthIndex=250, quantizeBits=8.

Version	recall	index(s)	index_docs/s	force_merge(s)	latency(ms)	QPS
baseline	0.985	74.35	672.54	0.02	8.233	121
candidate	0.985	73.83	677.26	0.02	8.282	120