[compiler-rt] [compiler-rt][test] Move tmp dir creation with env to where dir is run (PR #106252)

[Paul Kirth via llvm-commits]

ilovepi wrote:

The current test is looking for a file that will never exist, because LLVM_PROFILE_FILE isn't set when `%run` executes the test. It will always pass as written in tree. If you update the test to set the environment variable on the RUN line, it fails, because that directory does exist at that point in the program execution.

https://github.com/llvm/llvm-project/pull/106252