[clang] [clang] Merge gtest binaries into AllClangUnitTests (PR #134196)

[Reid Kleckner via cfe-commits]

rnk wrote:

If anyone is looking for stories about the value of premerge testing, I was all set to push this tonight, but I saw the linux premerge test failure. I debugged it, and it turns out to be a subtle interaction where if you run Clang codegen with registered targets but no registered TargetMachine classes, then one of our unittests will crash setting the large code model threshold 🙄 . Anyway, I pushed a fix and can land it tomorrow. Thanks for reviewing!

https://github.com/llvm/llvm-project/pull/134196