Fix FREEPBX-7997

Systems with /var and /tmp on different partitions cause problems. Use Asterisk's temporary directory instead.
Not quite, as we specifically check the args, so in the previous revisions (one's we are using in production), only the first arg passes the check, the other just use the defaults because the second arg of 0 isn't a directory, and we have no third arg. Technically we can just call schedtc.php with no args as all we are passing in here are the defaults we would set anyways.