Don't include RawUrl in the response (#1397)

Author: ivanpovazan

src/Microsoft.DotNet.XHarness.iOS.Shared/Listeners/SimpleHttpListener.cs

@@ -125,7 +125,8 @@ private bool Processing(HttpListenerContext context)
                 break;
             default:
                 Log.WriteLine("Unknown upload url: {0}", request.RawUrl);
-                response = $"Unknown upload url: {request.RawUrl}"; // CodeQL [SM02175] False Positive: This is a plain-text API response
+                response = "Unknown upload url";
+                context.Response.StatusCode = (int)HttpStatusCode.NotFound;
                 break;
         }