consider `undefined` request paramater validation value as non existing

See https://github.com/dotansimha/graphql-yoga/pull/2145/files#r1028976437

```
if I set requestParserResult.id  to undefined  it will still say unexpected parameter id
I have to reconstruct the object without a id parameter
```


https://tortilla-hq.slack.com/archives/C02HP79RCLR/p1669103250221129