Rename split select callback.

The split select callback is no longer used on anim complete, instead it
is used when an option is selected that results in a task launch. This
CL renames the function name to reflect this.

Bug: 419022969
Test: Manual
Flag: EXEMPT, refactor
Change-Id: Iee2b75314e5d4e2fdfc0cbd68bb0df0ff8c69730