[flexiglass] Fixes pattern redraw bug.

This regression was introduced in ag/24758912 where
PatternBouncerViewModel was changed from clearing the input before
calling authenticate to clearing it after.

Fix: 302598834
Test: manually tested pattern with correct and incorrect patterns, no
reanimation bug anymore
Test: Manually tested PIN with correct and incorrect input, with auto
confirm on or off
Test: Manually tested password with correct and incorrect input

Change-Id: I7f0f4fc4bdb99f3690e115a669a5e18fa00a4565