cli/scripts: more cros_build_lib.run API migrations

BUG=b:187789262
TEST=CQ passes

Change-Id: Idcc78ccfe14fdbae89ae7573d6e78036bdacf8ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3738519
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Ram Chandrasekar <rchandrasekar@google.com>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Ram Chandrasekar <rchandrasekar@google.com>
diff --git a/cli/command_vm_test.py b/cli/command_vm_test.py
index 3a3fa47..2d98c7d 100644
--- a/cli/command_vm_test.py
+++ b/cli/command_vm_test.py
@@ -136,7 +136,7 @@
     read_cmd = cmd + ['--', 'cat %s' % path]
     result = cros_build_lib.run(read_cmd, capture_output=True, encoding='utf-8',
                                 check=False)
-    if result.returncode or result.output.rstrip() != content:
+    if result.returncode or result.stdout.rstrip() != content:
       logging.error('Failed to read the file on the VM device.')
       raise CommandError(result.error)