[clang] [clang-format] Fix spacing before :: after non-macro identifiers (PR #189024)

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Lane0218 wrote:

> Be prepared, that maybe there will be reports where we need to further adapt this change, but for now I'd say we try it.

Thanks, makes sense. I'll keep an eye out for any follow-up reports and adjust the heuristic further if needed.

https://github.com/llvm/llvm-project/pull/189024