[clang-tools-extra] [clang-doc] fix flaky test in clang-doc (PR #101387)

[Paul Kirth via cfe-commits]

ilovepi wrote:

This isn't fixing anything. Its re-enabling it. I'd also suggest adding people from that bug as reviewers to help you get this re-enabled.

https://github.com/llvm/llvm-project/pull/101387