[Clang] Fix the instantiation of return type requirements in lambda bodies (#76967)

Currently, due to the incomplete implementation of p0588r1, the
instantiation of lambda expressions leads to the instantiation of the
body. And `EvaluateConstraints` is false during the instantiation of the
body, which causes crashes during the instantiation of the return type
requirement:

```cpp
template<typename T> concept doesnt_matter = true;

template<class T>
concept test = 
    []{
        return requires(T t) {
            { t } -> doesnt_matter; // crash
        };
    }();

static_assert(test<int>);
```

Although a complete implementation of p0588r1 can solve these crashes,
it will take some time. Therefore, this pull request aims to fix these
crashes first.

Fixes https://github.com/llvm/llvm-project/issues/63808
Fixes https://github.com/llvm/llvm-project/issues/64607
Fixes https://github.com/llvm/llvm-project/issues/64086

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