Update tests to not use untrusted virtual display

After adding check of isUntrustedVirtualDisplay() for creating home task
in ActivityStartController, using virtual display with system
decorations would no longer launch home activity. Replace that with
simulated display in CTS.

Bug: 153624902
Test: atest CtsWindowManagerDeviceTestCases:MultiDisplaySystemDecorationTests
Change-Id: Icea7f14c5e1b88c7a2e7060f9a7b9cef8168d0d7
2 files changed