Auto merge of #140951 - compiler-errors:super-fmt, r=ytmimi

Do not remove `super` keyword from `super let`

This is affecting a macro in the standard library:

https://github.com/rust-lang/rust/blob/bc7512ee6309ee7e8cacf87b94aa6d1f550c9d99/library/core/src/pin.rs#L1945

I added an exception in 6f6a9a585891d0a2d1114a7a621f35f28f39c0d9, but I'd like to remove it eventually, so opening this in-tree to not block this on the next rustfmt sync.

r? `@calebcartwright` or `@ytmimi`

Author: bors