qt_dev: Fix ContentSuggestions service connection

Issue:
When the RemoteContentSuggestionsService dies (due to package manager
update or clear data), the ContentSuggestionsPerUserService (system)
does not restart and uses an old zombie instance.

Fix:
 Reset the instance upon onServiceDied in the system service.

Test: Verified that stopping/clear-data/package-update of Device
Personalization Services (which implements ContentSuggestionsService)
multiple-times and then Overview long-press actually works.

Also verified that if the Remote Service crashes, we don't keep
 reconnecting infinitely.

Fixes: 120865921
Fixes: 130420008

Change-Id: I80197ec1cb446ddb5f1865a4b75beb18b48d2e9e