Fix skipping testBootEnableAndDisablePKVM (take 2)

The string that the assumption looks for is actually printed on stderr,
not stdout as the code currently expects. As a result, the test was
skipped as expected on _pkvm builds, but also unexpectedly on all other
builds as well.

Bug: 236799228
Bug: 244769139
Test: atest AVFHostTestCases on oriole_pkvm-userdebug
Change-Id: Ic28c4594277520841c7eface9dcf0e8998e5e0a4
diff --git a/tests/benchmark_hostside/java/android/avf/test/AVFHostTestCase.java b/tests/benchmark_hostside/java/android/avf/test/AVFHostTestCase.java
index 760c072..c7ee0f2 100644
--- a/tests/benchmark_hostside/java/android/avf/test/AVFHostTestCase.java
+++ b/tests/benchmark_hostside/java/android/avf/test/AVFHostTestCase.java
@@ -163,7 +163,7 @@
         assumeTrue(!result.getStderr().contains("Invalid oem command"));
         // Skip the test if running on a build with pkvm_enabler. Disabling pKVM
         // for such builds results in a bootloop.
-        assumeTrue(result.getStdout().contains("misc=auto"));
+        assumeTrue(result.getStderr().contains("misc=auto"));
     }
 
     private void reportMetric(List<Double> data, String name, String unit) {