Refactor HandleCollectionsAsync to an xunit Theory (#67126)

* Refactor HandleCollectionsAsync to a Theory

* add small buffer testing in StreamTests

* redisable test for mono/wasm platforms

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/Serialization/StreamTests.cs

@@ -8,9 +8,14 @@ public sealed class StreamTests_Async : StreamTests
         public StreamTests_Async() : base(JsonSerializerWrapper.AsyncStreamSerializer) { }
     }
 
+    public sealed class StreamTests_AsyncWithSmallBuffer : StreamTests
+    {
+        public StreamTests_AsyncWithSmallBuffer() : base(JsonSerializerWrapper.AsyncStreamSerializerWithSmallBuffer) { }
+    }
+
     public sealed class StreamTests_Sync : StreamTests
     {
-        public StreamTests_Sync() : base(StreamingJsonSerializerWrapper.SyncStreamSerializer) { }
+        public StreamTests_Sync() : base(JsonSerializerWrapper.SyncStreamSerializer) { }
     }
 
     public abstract partial class StreamTests