[RONs] Drop BigPictureStyle from Promotable styles

BigPictureStyle Notifications are vertically too large to accommodate on the shade and AOD. On the lock screen, these notifications will fallback to collapsed form and big picture will be shown as right icon. That's why we decided to drop bigpicture from promotable list and encourage using no style with large icon for RON usecases.

Bug: 367705002
Test: Presubmit
Flag: android.app.ui_rich_ongoing
Change-Id: I2d02667384c8960729af0727c1d146e1a98fad94