AndroidPackageParsingTestBase: Re-throw failures in setUpPackages in individual tests

Throwing in an @BeforeClass method breaks our test runner, due to
not reporting any results for the tests therein, leading to a difference
between actual and expected test counts.

The tool failure also obscured the fact that these tests
were already failing.

Bug: 153058196
Test: atest AndroidPackageInfoFlagBehaviorTest AndroidPackageParsingEquivalenceTest
Change-Id: Id0c1ebe2c99ff58451c1a1ccc20c6f9e355a725f