RRD: sanitize RRD file creation parameters.
RRD: sanitize RRD file creation parameters.

Do not allow 0 as value for the /step/ nor for the /length/
parameters at RRD file creation. This fixes #5693.

centreon/centreon-broker,centreon/centreon-broker,centreon/centreon-broker,centreon/centreon-broker,centreon/centreon-broker