Closes #22799

<S as S>::S where S is a struct panics with the only possible situation here is incorrect lifetime order, even though there are no lifetimes anywhere.

check_generic_args_len() skips the self type unconditionally, but the loop that consumes the arguments only skips it when the def has a Self parameter. A struct has none, so the self type is left over, matched against a regular parameter, and trips an assertion that assumes any leftover argument is a misordered lifetime. Skipping it in the loop as well keeps the two in agreement.

This only stops the panic. rustc reports E0404: expected trait, found struct, and there is no handler for it under ide-diagnostics/src/handlers/, so we still say nothing about the path itself.

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