Fix side channel leakage from the api of overrideLabelAndIcon

- The package information is disclosed from the different exceptions
  thrown by the api of IPackageManager#overrideLabelAndIcon.

- Fix the PackageManagerComponentOverrideTests breakage.

- Add non-existent package tests in the
  PackageManagerComponentOverrideTests. Verify that the api should
  throw security exception if the package does not exist.

Bug: 184851840
Bug: 190596162
Test: atest PackageManagerComponentOverrideTests
Change-Id: I77a9cc0f87413913bbcb93674f16c311574654dd