Ignore PrivateVolumeForgetTest#test_invalidSetupDoesNotCrashSettings

It failed with Resources$NotFoundException and it blocks
WindowManager extensions CTS tests, so ignore it at first.

Bug: 216630912
Test: atest com.android.settings.deviceinfo.PrivateVolumeForgetTest
Change-Id: Iec270535a73bcca5879d2792c181d853b4af7250