fix appliance of default last 5 periods configured in settings
When going to a viz page without any specific time selection put in the url or defined in the dataflow DEFAULT
annotation, then the default LastNPeriods configured in the settings should be applied, but instead a blank time selection is wrongly applied:
https://de-qa.siscc.org/vis?vw=tb&df[ds]=ds%3Astaging%3ASIS-CC-stable&df[id]=DF_DOMESTIC_TOURISM&df[ag]=OECD.CFE&df[vs]=5.0