[llvm] [llvm][unittests] add NDEBUG for some unittests (PR #80821)

[via llvm-commits]

huaatian wrote:

> it doesn't really make sense to run expensive checks without asserts, I wouldn't consider that configuration supported

Thank you for reviewing the code. Indeed, in most cases, when EXPENSIVE_CHECKS is enabled, !NDEBUG is also set. However, I understand that there is no explicit binding between these two situations. For example, in a few cases, I would like to use the checks that report errors with errs(), rather than using assert(). This can be considered as a tolerable medium complexity check. Is this understanding correct? I would appreciate your opinion.

https://github.com/llvm/llvm-project/pull/80821