Fix magnetized object fling detection

When releasing a dragged object below the magnetized object but
close to it with low velocity (or 0 velocity), we currently
detect it as flinging towards the magnetized target. This change
updates the logic to check that velocity is high and in the direction
of the target.

Fix: 429108959
Flag: EXEMPT bug fix
Test: atest MagnetizedObjectTest
Test: manual
       - create bubble in bubble bar
       - drag bubble to dismiss target
       - drag outside below the center
       - release bubble
       - observe bubble animate back to bubble bar
Test: manual
       - create floating bubble
       - fling around and verify that fling behavior works as expected
       - repeat the same test as described above for bubble bar and
         verify fling is detected correctly
Change-Id: I52a874db27a7ad47f4f5d76c71f8a100ce0073dc