[clang] [clang-format] fix incorrectly indents lambda trailing return (PR #94560)

[Owen Pan via cfe-commits]

owenca wrote:

> Technically also applies to attributes applied to the return type of the lambda, i.e.
> 
> ```
> int main() {
>   very_long_function_name_yes_it_is_really_long(
>       // also happens with constexpr specifier
>       [](auto n) [[attribute]]
>       -> std::enable_if_t<
>           std::is_arithmetic<decltype(n)>::value &&
>           !std::is_same<std::remove_cv_t<decltype(n)>, bool>::value> {
>         do_something(n * 2);
>       });
> }
> ```
> 
> ...but currently at least no valid C++ attribute can go in that spot

We can easily take care of it though. See https://github.com/llvm/llvm-project/pull/94560#discussion_r1632406068.

https://github.com/llvm/llvm-project/pull/94560