Enable bundles notif guts for NotificationBundleUi flag

This enables guts for notifications under a bundle but groups within
bundles are still claiming the long press, so this needs additional
fixing.

Test: Manual tested opening a guts for a bundled notif (groups don't
work yet)
Bug: b/389839492
Flag: com.android.systemui.notification_bundle_ui

Change-Id: I9aed401ebbb9a46d32dd73365f27f36a72bef129