Add 'Older than 30 days' option to the date facet

If the current search query matches only old results (e.g. considering the creation date) then the date facet has only the 'Custom date & time interval' option. But even if there are other options the counts don't 'sum up', i.e. you can see that there are search results which are not 'reflected' in the date facet values. So even if this option is not as useful as the others, it helps the user understand that the rest of the results are older.