[clang-format] Missing space between trailing return type 'auto' and left brace

There's no a space symbol between  trailing return type `auto` and left brace `{`.

The simpliest examles of code to reproduce the issue:

```
[]() -> auto {}
```

and

```
auto foo() -> auto {}
```

Depends on D130299

Reviewed By: HazardyKnusperkeks, curdeius, owenpan

Differential Revision: https://reviews.llvm.org/D130417