C#: Update outdated comments in supported external APIs test case file.

Author: michaelnebel

csharp/ql/test/query-tests/Telemetry/SupportedExternalApis/SupportedExternalApis.cs

@@ -15,19 +15,19 @@ public void M1()
     public void M2()
     {
         var d0 = new DateTime(); // Uninteresting parameterless constructor
-        var next0 = d0.AddYears(30); // Has no flow summary, supported as negative summary
+        var next0 = d0.AddYears(30); // Has no flow summary, supported as neutral summary model
 
-        var d1 = new DateTime(2000, 1, 1); // Interesting constructor, supported as negative summary
-        var next1 = next0.AddDays(3); // Has no flow summary, supported as negative summary
-        var next2 = next1.AddYears(5); // Has no flow summary, supported as negative summary
+        var d1 = new DateTime(2000, 1, 1); // Interesting constructor, supported as neutral summary model
+        var next1 = next0.AddDays(3); // Has no flow summary, supported as neutral summary model
+        var next2 = next1.AddYears(5); // Has no flow summary, supported as neutral summary model
     }
 
     public void M3()
     {
-        var guid1 = Guid.Parse("{12345678-1234-1234-1234-123456789012}"); // Has no flow summary, supported as negative summary
+        var guid1 = Guid.Parse("{12345678-1234-1234-1234-123456789012}"); // Has no flow summary, supported as neutral summary model
     }
 
-     public void M4()
+    public void M4()
     {
         var o = new object(); // Uninteresting parameterless constructor
         var response = new HttpResponse(); // Uninteresting parameterless constructor
@@ -38,11 +38,11 @@ public void M4()
         response.Write(o); // Known sink
     }
 
-     public void M5()
+    public void M5()
     {
         var l1 = Console.ReadLine(); // Known source
         var l2 = Console.ReadLine(); // Known source
-        Console.SetError(Console.Out); // Has no flow summary, supported as negative summary
+        Console.SetError(Console.Out); // Has no flow summary, supported as neutral summary model
         var x = Console.Read(); // Known source
     }
 }