test: strengthen multi-processor test with instrumentation_scope assertions

Verify that instrumentation_scope is correctly propagated to all
processors in both the clone (rest) and move (last) paths. Also
clarify changelog wording.

Author: bryantbiggs

opentelemetry-sdk/CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## vNext
 
-- Store `InstrumentationScope` in `Arc` internally in `SdkTracer`, making tracer clones cheaper (Arc refcount increment instead of deep copy). The multi-processor span export path now builds export data once instead of per processor.
+- Store `InstrumentationScope` in `Arc` internally in `SdkTracer`, making tracer clones cheaper (Arc refcount increment instead of deep copy). The multi-processor span export path now builds export data once and clones for additional processors, instead of rebuilding per processor.
 - Add 32-bit platform support by using `portable-atomic` for `AtomicI64` and `AtomicU64` in the metrics module. This enables compilation on 32-bit ARM targets (e.g., `armv5te-unknown-linux-gnueabi`, `armv7-unknown-linux-gnueabihf`).
 - `Aggregation` enum and `StreamBuilder::with_aggregation()` are now stable and no longer require the `spec_unstable_metrics_views` feature flag.
 - Fix `service.name` Resource attribute fallback to follow OpenTelemetry

opentelemetry-sdk/src/trace/span.rs

@@ -733,6 +733,13 @@ mod tests {
         assert_eq!(spans1[0].name, "multi_processor_span");
         assert_eq!(spans2[0].name, "multi_processor_span");
         assert_eq!(spans1[0].attributes, spans2[0].attributes);
+        // Verify instrumentation scope is correctly propagated to both processors
+        assert_eq!(spans1[0].instrumentation_scope.name(), "test");
+        assert_eq!(spans2[0].instrumentation_scope.name(), "test");
+        assert_eq!(
+            spans1[0].instrumentation_scope,
+            spans2[0].instrumentation_scope
+        );
 
         let _ = provider.shutdown();
     }