Remove syntax highlighting for C# verbatim strings due to bugs

This closes #32336.

(cherry picked from commit 49efd6093e35e5a51e4d41673341961e0af1220d)

modules/mono/csharp_script.cpp

@@ -308,7 +308,8 @@ void CSharpLanguage::get_string_delimiters(List<String> *p_delimiters) const {
 
 	p_delimiters->push_back("' '"); // character literal
 	p_delimiters->push_back("\" \""); // regular string literal
-	p_delimiters->push_back("@\" \""); // verbatim string literal
+	// Verbatim string literals (`@" "`) don't render correctly, so don't highlight them.
+	// Generic string highlighting suffices as a workaround for now.
 }
 
 static String get_base_class_name(const String &p_base_class_name, const String p_class_name) {