Update the snap targets in minimized mode to reflect the correct targets

In minimized mode there is only 1 split snap target compared to regular
portrait that has 30%, 50%, 70% targets. Update the accessibility options
for minimized mode to reflect the correct targets. Also removed the
middle target if there is only 1 split snap target.

Test: using talkback, see custom options on divider handle in minimized
mode
Fixes: 78304300

Change-Id: I8421499616cf0fe503c1f6a081a2151098640a9c