Prevent NotificationGroup list from updating outside of setNotification

Although notifications in setNotificationsthe is copied to a new list,
it still contains the same items as mOldProcessedNotifications in
PreprocesingManager. Any changes made to an item in
mOldProcessedNotifications will affect the respectable item in
mNotifications in CarNotificationViewAdapter. Hence copies of each item
are made to prevent this from happening.

Bug: 210477507
Test: Manual
Change-Id: I634f1aa95d293799cdaad0962214bd722d19c6e0