Remove WMG#closeAll in WindowTokenClient

The non-activity window should be managed by the application itself.
Framework side doesn't need to handle it.
Also apps may remove the view after WMG#closeAll and cause
IllegalArgumentException "not attached to window manager".

Test: atest WindowContextTest
Test: atest WindowContextTests WindowContextPolicyTests
Bug: 183251523
Change-Id: I15ccb9a129f541f3be9733e8cd6121bb4c0fd6b8