[clang] [llvm] test-release.sh: Add a CMake cache file for 3-stage release builds (PR #75903)

[Petr Hosek via cfe-commits]

https://github.com/petrhosek approved this pull request.

Out of curiosity, what's the reason for using 3-stage (rather than 2-stage) build?

https://github.com/llvm/llvm-project/pull/75903