[clang] [clang-repl] [test] Make an XFAIL more precise (PR #70991)

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dyung wrote:

> > If you still need help reproducing or debugging the issue on our bot, please let me know.
> 
> Thanks, much appreciated. Can you test if [mstorsjo at clang-repl-xfail](https://github.com/mstorsjo/llvm-project/commit/clang-repl-xfail) seems to run correctly in this environment? Otherwise I'll try to push it tomorrow and see how it fares on the bot.

Sure, I'll take it down this evening sometime and give it a try.

https://github.com/llvm/llvm-project/pull/70991