[clang] [Driver, test] Remove -v from mkdir & ln -s from a test since it fails on AIX (PR #72924)

[Fangrui Song via cfe-commits]

MaskRay wrote:

Thank you for the patch and open for my idea changing the title :)

I think `[test] ` as a tag is more common a patch that only deals with tests (more common than trailing `. NFC` or `[NFC]`), so I used it.

https://github.com/llvm/llvm-project/pull/72924