[Combobox] Fix presetting option (#4255)

* Fix #4250

* Refactor condition to check Value only

Remove some test code

Author: vnbaaij

src/Core/Components/List/ListComponentBase.razor.cs

@@ -483,14 +483,18 @@ protected virtual bool GetOptionSelected(TOption item)
             {
                 return OptionSelected.Invoke(item);
             }
-            else if (SelectedOption == null)
+            else if (SelectedOption == null && string.IsNullOrEmpty(Value))
             {
                 return false;
             }
             else if (OptionValue != null && SelectedOption != null)
             {
                 return GetOptionValue(item) == GetOptionValue(SelectedOption);
             }
+            else if (!string.IsNullOrEmpty(Value))
+            {
+                return string.Equals(GetOptionValue(item), Value, StringComparison.Ordinal);
+            }
             else
             {
                 return Equals(item, SelectedOption);