"Hide silent notifications in status bar" should apply to silent conversations,too

Notification is designed to be in a single section. So convo has two options when it is silent, convo or silent one.
This is our current section prio :  HeadsUp > FGS > People > Alerting > Silent > Minimized > Unknown/Default
As convo(people) has higher priority than silent, convo notifs always falls convo.

We decided to divide People notification into two groups, silent and alerting. Given that, new prio is going to be:

HeadsUp > FGS > People(alerting) > People(silent) >  Alerting > Silent > Minimized > Unknown/Default

Fixes: b/275711619
Test: atest NotificationIconAreaControllerTest
Change-Id: Ib9efcc199d8675fd16dc394075a53ff25a060786