Fix PackageParserTest#testPackageWithComponents.

Thix fixes an issue where testPackageWithComponents was failing because it
expected exactly one activity to be present in the test package, but was not
taking into account the hidden "app details" package that has been included
as of ag/5230995.

Bug: 138431444
Test: atest PackageParserTest
Change-Id: Ic3f8e0dd350b475421fdc5d9d48ab64481d6c23d