[clang-tools-extra] [clang-tidy][NFC] Enable 'readability-simplify-boolean-expr' check (PR #158706)

[Davide Cunial via cfe-commits]

capitan-davide wrote:

I tried with option `SimplifyDemorganRelaxed`, here's the [diffs](https://github.com/llvm/llvm-project/compare/518ae97641b488ca8c07a703c88f2a585b55594b...a5d4399d28040de1821fce030f9b97d7112a7997). For older commit is set to false `false`, the newer commit is `true`

https://github.com/llvm/llvm-project/pull/158706