Remove PromotedNotificationUiAod flag dep

It's not a *hard* dependency -- AOD promoted notifications won't *crash*
just because the promoted notification UI flag is turned off -- so let's
not bother people with errors about it.

Fixes: 397889922
Test: manual
Flag: com.android.systemui.aod_ui_rich_ongoing
Change-Id: I5cc26b63c3da1c798c31cfa561a0e271d8089a3a