This change replaces hard-coded defaults by $::os_service_default, so
that the service default values are used. This allows us to avoid
maintaining our own defaults and saves us from updating these values
according to any change in cinder itself.
Also, setting value => undef leaves the parameters unmanaged. This can
leave old parameter definitions if the parameters are removed from
manifest/hieradata. This change replaces undef by $::os_service_default
to ensure the parameters are cleared by default.
Change-Id: I89311e8c6cad89090c1b6612af425cb229cb71c7
accab30c06