Fixing Set runtime test output names in DDC (#2457)

Fixes tests that break due to https://dart-review.googlesource.com/c/sdk/+/373327

DDC now represents `_HashSet` objects as `LinkedSet` in its internal representation (no implementation changes).

Author: Markzipan

dwds/test/instances/common/instance_inspection_common.dart

@@ -295,7 +295,7 @@ void runTests({
           final instanceId = instanceRef.id!;
           expect(
             await getObject(instanceId),
-            matchSetInstance(type: '_HashSet<int>'),
+            matchSetInstance(type: 'LinkedSet<int>'),
           );
 
           expect(