Do not unregister CONSTRAIN_DISPLAY_APIS for WmTests

Because it uses a static member to decide whether to register.
If there are multiple tests depend on it, the tests after the
first one will fail because the listener was removed in tearDown.

Bug: 219640050
Test: atest SizeCompatTests
Change-Id: Icd2e1e4edd3c986b0c714b97a2a4f50d78242fa0