fix nullablity in FromFailedTest (#5971)

Author: SimonCropp

src/Platform/Microsoft.Testing.Platform.MSBuild/Tasks/FailedTestHelper.cs

@@ -71,17 +71,16 @@ internal static void FromFailedTest(this FailedTestInfoRequest failedTestInfoReq
             string nameAndPlace = place == null
                 ? $"{failedTestInfoRequest.DisplayName} ({failedTestInfoRequest.Duration})"
                     : $"{failedTestInfoRequest.DisplayName} ({failedTestInfoRequest.Duration}): {place}";
-            string? singleLineError = JoinSingleLineAndShorten(nameAndPlace, failedTestInfoRequest.ErrorMessage);
 
-            message = singleLineError!;
+            message = JoinSingleLineAndShorten(nameAndPlace, failedTestInfoRequest.ErrorMessage);
         }
     }
 
-    private static string? JoinSingleLineAndShorten(string first, string? second)
+    private static string JoinSingleLineAndShorten(string first, string? second)
         => second == null
             ? SingleLineAndShorten(first)
             : SingleLineAndShorten(first) + " " + SingleLineAndShorten(second);
 
-    private static string? SingleLineAndShorten(string? text)
-        => text == null ? null : (text.Length <= 1000 ? text : text[..1000]).Replace('\r', ' ').Replace('\n', ' ');
+    private static string SingleLineAndShorten(string text) =>
+        (text.Length <= 1000 ? text : text[..1000]).Replace('\r', ' ').Replace('\n', ' ');
 }