Clangd puts parameter name hint on UDLs

This is confusing because UDLs are not visibly a function call.

```cpp
int inline consteval operator""_lit(unsigned long long val) { return 0; }

int main() {
    return 3_lit;
}
```

When the above is annotated by clangd, it puts `val: ` in front of `3_lit`, it looks like this:
```cpp
int main() {
    return val: 3_lit;
}
```
