Allow passing creduce options through creduce-clang-crash.py (#92141)

This change allows us to pass creduce options to creduce-clang-crash.py
script. With this, `--n` is no longer needed to specify the number of
cores, so removed the flag.

The motivation is
https://github.com/llvm/llvm-project/pull/87933#issuecomment-2109463497
suggests that disabling creduce renaming passes helps people to further
reduce crash manually.