Fix some tests after move splash screen window to systeui(11/N)

After splash screen move to systemui, there will be some timing changes
such as add/remove window were not complete synced inside system server.

KeyguardTransitionTests: There will trigger another transition when
remove the starting window, disable showing splash screen for those
tests to make them stable.
Fix testHandleExitIconAnimatingActivity failed due to type cast.

MultiDisplaySystemDecorationTests#testCrossDisplayBasicImeOperations
This test use tapOnDisplaySync to launch mock IME, but the starting
window may above the activity.

Disable starting window for WindowInsetsControllerTests
CloseOnOutsideTests, which may cause test flaky.

Bug: 73289295
Bug: 131311659
Test: atest KeyguardTransitionTests SplashscreenTests
Test: atest MultiDisplaySystemDecorationTests
Test: atest WindowInsetsControllerTests CloseOnOutsideTests
Change-Id: I60850ab09540aefedf8b98973a13b91814366f82