Do not use virtual display from real system in mocked test

If the test inherit WindowTestsBase, the window manager is like in a
sandbox environment. It should not have interaction with real
system as possible. Otherwise it may leave some permanent side effects
and affect other tests because the mocked environment cannot guarantee
to manage the real resources well.

Also moved content recording related tests to ContentRecorderTests.

Bug: 254268165
Test: atest ContentRecorderTests WindowManagerServiceTests
Change-Id: I33ca2cfc51943f4a19abc4fc226309cb68eb32bf