[clang-tools-extra] [clang-tidy] Clarify diagnostics of bugprone-sizeof-expression (PR #95550)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

> Consider replacing ":" separator with ","

I switched to ":" (instead of the ";" that was used previously) to emphasize that the second part of the message is an explanation/reason for the first part (and not a second, separate issue). However I can switch to "," or ";" if that option turns out to be more popular.

@ rewiewers: Which symbol would you prefer in these messages?
(My preferences are dot > keep the semicolon ≳ comma.)

https://github.com/llvm/llvm-project/pull/95550