Fixing test that fail when FOLDABLE_SINGLE_PAGE is set to true

We need to change the result of REQUEST_IS_TWO_PANELS when the
flag is on because now we don't have two panels only 1.

Another of the issues is a rounding error when calling
getUnusedHorizontalSpace().

And lastly updating workspaceToBoards so that it maps the coordinate
of workspace items to their right position.

Bug: 270395274
Test: atest ReorderWidgets
Change-Id: I2620e5bf1ba132f984e00d2a6c21081953d259fd