Migrate existing 4x5 and 4x4 grid users to a new 4x5 grid.

Due to the dogfood 4x5 grid using the wrong db, there may
be some rearranging of items.

The goal is to completely remove the old 4x4 and 4x5 grid,
but first we need to silently migrate users to the new grid.

We still  need to keep the old grids in the device profile
so we hide them from the Styles & Wallpaper app.

We also need to reset and remove the ENABLE_FOUR_COLUMN feature
flag from the UI.

- Added TODO to remove this logic in the tracking doc

Bug: 183965808
Bug: 175329686
Test: have old 4x4 or 4x5 grid set up
      install apk with these changes
      confirm that we are now using the new grid and the
      other grid options are inaccessible to the user
Change-Id: I81a91b8415effbe0bf7ba722f11ab44a4169e3df