Skip enter split expanding animation by drag

By our motion specs, drag drop to enter split case
should show split contents after drop rather than
run animation to enter split.
We already have a function for drag drop tell split
screen for logging events. Use this function to set
a flag to skip next time entering animation and reset
it after entering.

Fix: 247108671
Test: manual
Test: pass existing tests
Change-Id: Ie1a511bc4846021a79db726ef7a42590b33b8afb