Rollup merge of #57418 - lqd:collector_query, r=michaelwoerister
Rollup merge of #57418 - lqd:collector_query, r=michaelwoerister

MetadataOnlyCodegenBackend: run the collector only once

Use the `collect_and_partition_mono_items` query to avoid calling the collector directly twice.

Fixes #57406.

graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust