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/scripts/cros_sdk.py b/scripts/cros_sdk.py
index 5093c74..ab50f20 100644
--- a/scripts/cros_sdk.py
+++ b/scripts/cros_sdk.py
@@ -125,7 +125,7 @@
                                 debug_level=logging.NOTICE,
                                 capture_output=True)
     successful = False
-    for header in result.output.splitlines():
+    for header in result.stdout.splitlines():
       # We must walk the output to find the 200 code for use cases where
       # a proxy is involved and may have pushed down the actual header.
       if status_re.match(header):
@@ -407,7 +407,7 @@
   # valid snapshots.
   snapshots = []
   snapshot_attrs = re.compile(r'^V.....t.{2,}')  # Matches a thin volume.
-  for line in result.output.splitlines():
+  for line in result.stdout.splitlines():
     lv_name, pool_lv, lv_attr = line.lstrip().split('\t')
     if (lv_name == chroot_lv or lv_name == cros_sdk_lib.CHROOT_THINPOOL_NAME or
         pool_lv != cros_sdk_lib.CHROOT_THINPOOL_NAME or