Address post-commit review comments

Address post-commit review comments in PackageStatusStorage.java

Tested with:
make -j30 FrameworksServicesTests
adb install -r -g \
  "out/target/product/angler/data/app/FrameworksServicesTests/FrameworksServicesTests.apk"
adb shell am instrument -e package com.android.server.timezone -w \
  com.android.frameworks.servicestests \
  "com.android.frameworks.servicestests/android.support.test.runner.AndroidJUnitRunner"

Test: See above.
Bug: 31008728

Change-Id: I3d9d1b1f40b0568629e58a13d1184add0fd1f0ac