Delayed registering as a system service

Register the service after subscription database manager
is created.

Fix: 269089007
Test: v2/pixel-health-guard/device-boot-health-check-extra
Merged-In: I7db87800e2d9e1f78b0ede17d92b9197a2d319a2
Change-Id: I7db87800e2d9e1f78b0ede17d92b9197a2d319a2