fix(dspy): `return_all_scores` and `return_outputs` in Evaluate class

[LetianLee]

Make the parameters return_all_scores and return_outputs of the Evaluate class more reasonable.

1. If I specify return_outputs=False when calling __call__, this value is not actually passed in, as return_outputs will take the value from self.return_outputs at that time.
2. Ensure that the return_all_scores parameter is passed in and initialized consistently with return_outputs.