Auto merge of #52244 - glandium:issue52097, r=estebank

Don't display default generic parameters in diagnostics that compare types

In errors like:
```
   expected type: `RawVec<foo, Global>`
      found type: `foo`
```

`RawVec` being defined as `RawVec<T, A: Alloc = Global>`, the error is better written as
```
   expected type: `RawVec<foo>`
      found type: `foo`
```

In fact, that is already what happens when `foo` is not an ADT, because in that case, the diagnostic handler doesn't try to highlight something, and just uses the `Display` trait instead of its own logic.

e.g.
```
   expected type: `RawVec<usize>`
      found type: `usize`
```

0 files changed, 0 insertions, 0 deletions