Make use of the FULL_EDIT_DISTANCE flag.

In effect, this stops the spell checker from suggesting overly
long words.
More precisely, it takes advantage of the new facility that
takes into account the whole length of the dictionary word when
computing scores, so words much longer than the input word will
see their score demoted accordingly.

Bug: 5384578
Change-Id: I326cd7c87c3080e7fa8729f78517f8ba13672a9b