Remove flag guarding widget picker size filter.

Users will be able to choose to filter by size (or not) directly in the
widget picker. So we should always send size requirements to the picker
activity.

Bug: 345482907
Test: Manually by invoking the widget picker and choosing to filter by
size from the 3-dot drop down.
Flag: EXEMPT bugfix

Change-Id: I7f8611b1f89fe4e99dae2b93ce0a70b91132861e