Fix UID logging.

The uid parameter to scheduleAsPackage is the calling UID. It was
incorrectly being used as the source UID in the statsd logging, causing
the end metrics to have the wrong information. This fixes the UID
logging and renames the input parameter to avoid further confusion.

Bug: 138239687
Test: N/A
Change-Id: Ifdfe2ffbc7b5f8b8fe74291a1ec54068541f740b