Replace slide transitions with fade for glanceable hub V2

This is for pre-flexiglass transitions. Flexiglass changes will be in
followup change.

Bug: 382743223
Test: manually
Flag: com.android.systemui.glanceable_hub_v2
Change-Id: I76a5c1f7f3f5c7f8ebfda9753f84dd90bc3ce5fe