[clang-tools-extra] [clang-tidy] fix `bugprone-narrowing-conversions` false positive for conditional expression (PR #139474)

[via cfe-commits]

AndreyG wrote:

@vbvictor I've found out that unlike other narrowing-conversion tests, I didn't set explicitly target for the test run.
I've fixed it and created another PR #151874. Please, take a look and sorry for the inconvenience.

https://github.com/llvm/llvm-project/pull/139474