perf: remove unnecessary manual string.Replace code.

Author: TimothyMakkison

TUnit.Core/Helpers/ArgumentFormatter.cs

@@ -96,21 +96,7 @@ private static string FormatDefault(object? o)
                 return str;
             }
 
-#if NET8_0_OR_GREATER
-            // Use Span<char> for better performance - avoid string.Replace allocation
-            Span<char> buffer = str.Length <= 256
-                ? stackalloc char[str.Length]
-                : new char[str.Length];
-
-            for (int i = 0; i < str.Length; i++)
-            {
-                buffer[i] = str[i] == '.' ? '·' : str[i];
-            }
-
-            return new string(buffer);
-#else
             return str.Replace(".", "·");
-#endif
         }
 
         if (toString == type.FullName || toString == type.AssemblyQualifiedName)