Report mApp.uid instead of mApp.info.uid.

The two differ in the case of SDK sandbox process. The former would be
the uid of the actual app process hosting the SDK. The latter is a
generic uid for the sdksandbox package.

Test: atest ProcStatsTests
Bug=304599926

Change-Id: Ia29d088b909532319d5b17084a94f79090f86cff