Remove SOFT_INPUT_ADJUST_RESIZE flag

It's been deprecated in favor of each window handling its own
insets. Which we already do for the IME. Per IME team, this was
triggering a path that would auto-show the soft input.

So let's not do that.

Fixes: 247957195
Test: manual, following steps listed in bug
Change-Id: I997dee193ed1150a531c1cc32f79d7beba0d1021