Newer Linux distros (at least el9.6) are printing a warning message for scripts using `/bin/bash`:

lustre/tests/racer/file_setxattr.sh from /bin/bash to #!/usr/bin/bash

The use of /bin vs /usr/bin is deprecated since at least RHEL8, since this is just a symlink today, and master no longer supports RHEL7 and earlier.

There are also a few places using `/bin/sh` directly that should be changed as well (whether to `/usr/bin/sh` or `/usr/bin/bash` is an exercise for the reader).