[llvm-branch-commits] [Profile] Rewrite Test to work with Internal Shell (PR #165145)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/165145

There was one test that used subshells to read a file. Replace those
subshells with the readfile substitution.