[clang-tools-extra] [clang-tidy] Correcting fix suggestion in `readability-simplify-boolean-expr` (PR #178392)

[Björn Svensson via cfe-commits]

bjosv wrote:

> It would be nice to test all versions of C language.

I don't think this checker handles C version before C23 currently (see issue #127384) .
The C23 AST gives `CXXBoolLiteralExpr` for `true`/`false`, which this checker uses, while e.g. C99 only has `IntegerLiteral`.

https://github.com/llvm/llvm-project/pull/178392