C++: Adjust user-defined literals test' expectations

Author: AlexDenisov

cpp/ql/test/library-tests/udl/udl.expected

@@ -1,4 +1,4 @@
 | udl.cpp:5:25:5:28 | Xy | udl.cpp:5:25:5:28 | initializer for xy |
 | udl.cpp:6:27:6:34 | XyXy | udl.cpp:6:27:6:34 | initializer for xyxy |
-| udl.cpp:7:26:7:30 | X | udl.cpp:7:26:7:26 | call to operator "_Y |
-| udl.cpp:8:29:8:38 | XX | udl.cpp:8:29:8:29 | call to operator "_Y |
+| udl.cpp:7:26:7:30 | X | udl.cpp:7:26:7:26 | call to operator ""_Y |
+| udl.cpp:8:29:8:38 | XX | udl.cpp:8:29:8:29 | call to operator ""_Y |