[clang-format] Enable again some operator tests (#83380)

Multiple formatting operator tests are commented. This change enables
them again.

[PR506629](https://llvm.org/PR50629) fixed by
[D153798](https://reviews.llvm.org/D153798).

Tests in `ConfigurableSpaceBeforeParens` have the same behavior as
before [D110833](https://reviews.llvm.org/D110833).

Update the test for function declaration and definition, as changed in
[D114696](https://reviews.llvm.org/D114696).