[pm] don't call onChanged at the end of commitPackageStateMutation

onChanged() is the trigger of snapshot building. During commitPackageStateMutation, it should already be called when the set* methods of PackageSetting or PackageUserStateImpl are called as part of the mutation. One exception is setLastPackageUsageTimeInMills, we intentionally don't want to call onChanged() because of its frequent updates. Having another onChanged in commitPackageStateMutation is unnecessary and can cause unwanted snapshotting, as shown in b/298096460. Removing it to avoid future misuses.

Change-Id: Iaf201c43c394059f71181308a2b89dd65ba68e8e
BUG: 298409017
Test: presubmit