Exempt alarms and car emergency notifications from suppression

 Exempt the following notification categories from notification cooldown or
 avalanche suppression:
 - CATEGORY_ALARM
 - CATEGORY_CAR_EMERGENCY
 - CATEGORY_CAR_WARNING

Flag: com.android.server.notification.polite_notifications
Test: atest NotificationAttentionTest
Bug: 356616535
Change-Id: I62f3da180e3c39ab0b6cd2075baa93bf46a358eb