Password settings: Fix duplicate title

For the autofill service settings, "Autofill service" is both the
section title and the preference title. This change removes the
duplicate preference title and promotes the app label from the summary
string to the title in its place.

Fix: 192403526
Test: manual - single profile, personal+work profile, change service and
 re-check
Change-Id: Ia012232ba2856e0757289982bc3045d948ff4aa8