Import mapping source of a line item/list to 'fixed item' or 'ask every time' remove 'Which target'

Description of the enhancement:

Import Mapping: Mapping the source of a line item or list to 'fixed item' or 'ask every time' removes the 'Which target items to clear prior to import'. Can this remain there?

As a user, I would like the 'Which target items to clear prior to import' option to remain on the line item/list item tab of the import mapping dialog when that item is set as either 'Ask every time' or 'Fixed item'. Currently this option is only visible when it is set to a column.