labels_compatible() is exact-match only, not superset matching #649

`asap_types::capability_matching::labels_compatible()` (line 86, TODO already there) requires a deployed config's labels to equal the query's labels exactly. No config reuse across AQEs with different label subsets.

Example: a config deployed with grouping labels `{pod, node}` can't serve a query that only needs `{pod}`, even though it has everything required — a new config gets deployed instead.

This is what blocks cross-AQE sharing (see the cross-AQE sharing issue). Part of #523, Phase 3b.