Fixes test setup to uninstall the correct test app

Prior to this change, the setup step for the atomic install cts tests
would uninstall the wrong packages and then use common packages used in
other install test cases. If there was a failure to clean up those apps
in one of the other tests, this test case would be unable to uninstall
due to the orphaned state of the apps.

Fixes: 138883691
Test: atest AtomicInstallTests
Change-Id: I1cf50f7be6acb85a7cad5bac03b13982602f8417