[llvm-branch-commits] [CGData] Rewrite tests to not use subshells (PR #157234)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/157234

Subshells are not supported by lit's internal shell, which we want to
enable by default for the LLVM test suite. Rewrite the tests in
llvm/test/tools/llvm-cgdata to not use subshells so we can achieve this
without losing any test coverage.