Summary

SemconvStability still reflects the older semconv declarative config shape, while newer declarative semconv config support has landed upstream.

This should be aligned first, separately from the broader ConfigPropertiesUtil / library-instrumentation cleanup.

Recommendation

• Update SemconvStability to support the newer declarative semconv config model.
• For 3.0, remove the legacy semconv declarative shape from SemconvStability for domains covered by the newer declarative model (db, code, rpc, messaging).
• Keep flat-property fallback for compatibility for now.
• Handle service.peer separately in Decide how service.peer semconv should map to declarative config #18933.

Why separate from #15810

This is not really a library-instrumentation cleanup item; it is semconv config evolution / alignment work.