Remove leftover analyzer test code

Author: Sergio0694

tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Helpers/CSharpAnalyzerWithLanguageVersionTest{TAnalyzer}.cs

@@ -63,16 +63,6 @@ public static Task VerifyAnalyzerAsync(string source, LanguageVersion languageVe
 #endif
         test.TestState.AdditionalReferences.Add(MetadataReference.CreateFromFile(typeof(ObservableObject).Assembly.Location));
 
-        test.SolutionTransforms.Add((solution, projectId) =>
-            solution.AddAnalyzerConfigDocument(DocumentId.CreateNewId(projectId),
-                "UseMarshalType.editorconfig",
-                SourceText.From("""
-                    is_global = true
-                    build_property.LibraryImportGenerator_UseMarshalType = true
-                    """,
-                    Encoding.UTF8),
-                filePath: "/UseMarshalType.editorconfig"));
-
         test.ExpectedDiagnostics.AddRange(expected);
 
         return test.RunAsync(CancellationToken.None);