Clean up rollbacks and test apps

See comment#6.

Clean up rollbacks and test apps before and after running tests.
This ensure we are in a good and expected condition when running tests.

Bug: 154080003
Test: atest RollbackTest
Test: atest MultiUserRollbackTest
Test: atest NetworkStagedRollbackTest
Test: atest StagedRollbackTest

Change-Id: If10fc8865e644611f1cf6a9db9d6dca6c7f11aee
diff --git a/tests/RollbackTest/MultiUserRollbackTest.xml b/tests/RollbackTest/MultiUserRollbackTest.xml
index ba86c3f..2f62af1 100644
--- a/tests/RollbackTest/MultiUserRollbackTest.xml
+++ b/tests/RollbackTest/MultiUserRollbackTest.xml
@@ -15,6 +15,12 @@
 -->
 <configuration description="Runs rollback tests for multiple users">
     <option name="test-suite-tag" value="MultiUserRollbackTest" />
+    <target_preparer class="com.android.tradefed.targetprep.RunCommandTargetPreparer">
+        <option name="run-command" value="pm uninstall com.android.cts.install.lib.testapp.A" />
+        <option name="run-command" value="pm uninstall com.android.cts.install.lib.testapp.B" />
+        <option name="teardown-command" value="pm uninstall com.android.cts.install.lib.testapp.A" />
+        <option name="teardown-command" value="pm uninstall com.android.cts.install.lib.testapp.B" />
+    </target_preparer>
     <test class="com.android.tradefed.testtype.HostTest" >
         <option name="class" value="com.android.tests.rollback.host.MultiUserRollbackTest" />
     </test>