Fix failures in MultiDisplayDragMoveIndicatorControllerTest

The test failed with FLAG_ENABLE_WINDOW_DROP_SMOOTH_TRANSITION flag on
it's because in the test we didn't consider indicator surface's
creation on the start display. This commit fixes the issue.

Flag: com.android.window.flags.enable_window_drop_smooth_transition
Bug: 438153896
Test: atest MultiDisplayDragMoveIndicatorControllerTest
Change-Id: Icd09f1ff1e3c472fb1445311ebbe2cf980464ab8