The Frequent apps grid has a few problems:

 * On a fresh install there would be no history of app usage so the
   applications shown in the grid have no relevance it takes time
   to be useful instead of being useful from the start;

 * The grid has far too many items in it to be relevant; 24 apps is
   well beyond the average use case as most people don't frequently
   use that many, so it gets populated with several apps that are
   single use (hello xterm);

 * The position of items in the grid are always changing based on an
   unknown frequency metric (and not by user-intended input) which
   makes it a poor way to quickly launch apps as one would have to
   constantly learn the positions of the items in the grid;

 * Having two app grids is a bit superfluous and needlessly complicates
   the app launching navigation: you have to spend time checking the
   frequent grid and if it's not there you have to switch over to another
   grid and find the app you need in there it's not straightforward.

Remove the Frequent tab and simplify the related code.

Related: #1425

!880