[clang] [Clang] Wide delimiters ('{{{') for expect strings (PR #77326)

[via cfe-commits]

sethp wrote:

@ZequanWu would either of these work for you?:

```c++
 DCHECK_OK(foo); // expected-error at components/reporting/util/status_macros.h:* {{{CHECK,DCHECK,ASSERT,EXPECT}_OK do not accept a type other than Status or StatusOr.}}}
```

or

```c++
 DCHECK_OK(foo); // expected-error-re at components/reporting/util/status_macros.h:* {{{CHECK,DCHECK,ASSERT,EXPECT}_OK do not accept a type other than Status or StatusOr.}}
```

https://github.com/llvm/llvm-project/pull/77326