ferrochrome-tests: Fix ferrochrome image push path

This fixes regression caused by my previous commit:
  d3388bb71 Ferrochrome: Match vm_config.json with custom_vm.md

.. which unexpectidly modified image push path.

Bug: 351065253
Test: atest ferrochrome-tests && ./ferrochrome.sh
Change-Id: I050438877ccb18a2cb3d1e71e3b15741311c8b10
diff --git a/tests/ferrochrome/AndroidTest.xml b/tests/ferrochrome/AndroidTest.xml
index 79cbe72..8053674 100644
--- a/tests/ferrochrome/AndroidTest.xml
+++ b/tests/ferrochrome/AndroidTest.xml
@@ -32,9 +32,9 @@
          It's too large (6.5G+), so this may break further tests. -->
     <target_preparer class="com.android.tradefed.targetprep.RunCommandTargetPreparer">
         <option name="throw-if-cmd-fail" value="false" />
-        <option name="run-command" value="mkdir /data/local/tmp/ferrochrome" />
+        <option name="run-command" value="mkdir /data/local/tmp" />
         <option name="teardown-command" value="pkill vmlauncher" />
-        <option name="teardown-command" value="rm -rf /data/local/tmp/ferrochrome" />
+        <option name="teardown-command" value="rm /data/local/tmp/chromiumos_test_image.bin" />
     </target_preparer>
 
     <test class="com.android.tradefed.testtype.binary.ExecutableHostTest" >