Rollup merge of #120155 - compiler-errors:no-erased-when-promoting, r=aliemjay

Don't use `ReErased` to detect type test promotion failed

Using `ReErased` here is convenient because it implicitly stores the state that we are explicitly recording with the `failed` variable now, but I also think it adds a tiny bit of complexity that is not worth it.

r? `@aliemjay`

Author: matthiaskrgr