Add more tests in AccessibilityWindowManagerWithAccessibilityWindowTest

The previous CL [1] moved some logic, and now that we can easily write
unit tests for migrated computations in AccessibilityWindowManager.

This adds a test coverage for such code.

[1] Ib37cb934686d7677f2da74d6ed9ad6e7fcb5efd1

Bug: 322444245
Bug: 325341171
Test: AccessibilityWindowManagerWithAccessibilityWindowTest
Change-Id: Ib785dfaa7d72990053a142d4daeec388149351a9