[pm] handle installExistingPackageAsUser in PackageMetrics

Logging installExistingPackageAsUser in PackageMetrics, including uid, installerUid, version, apk size and is_system.

FIXES: 298203341
Test: manual with "statsd_testdrive 524" command

Change-Id: Ic3ce714ecc8b9c526bb58624713c7b6f8f9786eb
3 files changed