Remove current method for moving activities / section within the page

Currently a user can move an activity or section by clicking on the 'drag' icon and pressing enter or right-click - this brings up a long list of all the items that are on the page and the user can select where they would like the selected items to be placed.

The current UI is not fit for long lists and results in a very poor user experience (see screenshot) and will be replaced by UX-117