Add a job to prune UsageStats data on package removals.

Add a job to prune any usage stats data that exists on disk belonging
to uninstalled packages. This job will be scheduled every time there
is a package removal, appending to the work of any previous pending
jobs. Jobs for each user will be executed when the device is idle.

Bug: 143889121
Test: atest UsageStatsDatabaseTest#testPackageDataIsRemoved
Change-Id: Iee00917a940930271ca40367ca24992cde018616