Rollup merge of #112614 - lukas-code:apit-unsized-suggestion, r=compiler-errors

tweak suggestion for argument-position `impl ?Sized`

fixes this invalid suggestion:
```text
help: consider removing the `?Sized` bound to make the type parameter `Sized`
  |
1 - fn foo(_: impl ?Sized) {}
1 + fn foo(_: impl ) {}
  |
```

Author: GuillaumeGomez