Remove support for PackageDexUsage version 1

PackageVersion version 1 was indroduce in Nougat. Since then,
all devices should have updated to version 2 which was introduced in O.

This simplifies the logic in preparation for adding support for
system server jars.

Test: atest DexManagerTests PackageDexUsageTests
Bug: 148774920
Change-Id: Ib546ed12c5341d01fb12545cd98598b4cf2c5051