[clang] [clang][cmake] Move perf-training out of CLANG_INCLUDE_TESTS (PR #192163)

[via cfe-commits]

markyang92 wrote:

@petrhosek 
Thank you for reviewing my PR.
You're right, I used Claude to help draft the commit message and PR description. I'm not a native English speaker and this is my first time with an LLVM PR, so I wasn't familiar with the environment.
I added an `Assisted-by: Claude` trailer per the policy.
I also modified and redrafted the commit message.
so I'm happy to answer any questions.
Thanks for the pointer.

https://github.com/llvm/llvm-project/pull/192163