perf test - shell - skip backup editor files ending in tilda

You edit your scripts in the tests and end up with your usual shell
backup files with ~  the end, but then your next perf test run wants
to run the backups too. You end up chasing which test is the one you
edited and the backup and have to keep removing all the backup files,
so automatically skip any files that are backup files with a tilda at
the end.