Remove SetupWizardRecyclerItemsLayout

Its functionalities were folded into SetupWizardRecyclerLayout and
has been deprecated. Codesearch shows no usage of this class so it
should be safe to remove.

Test: Existing tests pass. (./gradlew connectedAndroidTest)
Change-Id: Ie56a5ecdb9bd4b8ad91461794a6cd89e3c5fd8e1