Keep the conversation shortcut criteria in People Service consistent with the...

Keep the conversation shortcut criteria in People Service consistent with the one in Notification Manager

Before this change, People Service uses the presence of the Person object
in ShortcutInfo as the criteria of conversation shortcut. This changes
the criteria that the shortcut needs to be a share shortcut instead of having Person object.

Change-Id: I1ea52a50c909ca96365c1d4e55af97931d048d8f
Test: atest ShortcutHelperTest
Test: atest DataManagerTest
Bug: 154254830