Delete com.android.apex.cts.shim@2.apex

testAdbRollbackAppWaitsForStagedReady (added by ag/12361995) leaves
com.android.apex.cts.shim@2.apex in the data partition which causes
PackageManagerTest#testGetApplicationInfo_ApexSupported_MatchesApex
to fail.

This CL ensures APEX files in the data partition are cleaned up after
running the tests.

Bug: 166157914
Test: atest StagedInstallInternalTest PackageManagerTest
Change-Id: Ia23adcb91c3f9ebfa082f92221c16d2e57838e66