[llvm-branch-commits] [ASan] Make duplicate_os_log_reports.cpp work with the internal shell (PR #168656)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/168656

This test used a for loop to implement retries and also did some trickery with PIDs.
For this test, just invoke bash for actually running the test given we need the PID,
and move the for loop into a separate shell script file that we can then invoke from
within the test. Normally it would make sense to rewrite such a script in Python, but
given this test does not have portability concerns only running on Darwin, it is fine
to use a shell script here given there is no other convenient alternative.