tests: fix logic error in wait_for_window()
tests: fix logic error in wait_for_window()

Revert change introduced in cbc5dbb9b154ceadf8bd1ed86c3c1f15c668a687

marmarek/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin