DO NOT MERGE ANYWHERE
Use DisplayId when verifying top task in MulitDisplay

MultiDisplay does not always use a specific DisplayId
when verifying top task which can lead to incorrect
verification as they can differ of course.

Test: atest CtsWindowManagerDeviceTestCases:android.server.wm.MultiDisplayClientTests
Test: atest CtsWindowManagerDeviceTestCases:android.server.wm.MultiDisplayActivityLaunchTests

Flag: TEST_ONLY

Bug: 368604141
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:0aea63219254b79fa52f28bd13de930ec3ebd47e)
Change-Id: I3579d00775e62484cea51768a5d7e85b763c553c