Center hub UI horizontally in landscape

When mobile devices with display cutout is in landscape,
communal container has either left or right margin set from
system window insets.
For hub to be edge to edge, reset the horizontal margin in
onApplyWindowInsets listener.

Fixes: b/395706952
Test: on foldable mobile
Flag: com.android.systemui.glanceable_hub_v2
Change-Id: Ic6244ef7a9c1a64b1e0536a36513193bf8f6dbff