Mitigate 10 minutes delay in launcher restore for work apps.

1. Instead of debouncing launcher restore when new install session
(triggered by Play Service due to restore) is created, it is now
throttled at once every 30 seconds. (i.e. Launcher restore is triggered
immediately, but cannot be triggered again within 30 seconds)
2. Removes the backup table when all items are restored. (i.e. no item
were removed as a result of sanitize db due to user didn't sign in to
their work profile)

Bug: 153648870
Change-Id: I32df371f8b47c60a72515876217fd83ac1e56f0a
Test: manually verified with deferred restore