SDK cleanup: Also clean images.

SDK is running out of space. Clean the images to free more space.

BUG=chromium:1078979
TEST=cq

Change-Id: Ib44f895c78342a1964c2fe528022e63585a40497
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2187925
Commit-Queue: Alex Klein <saklein@chromium.org>
Tested-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/api/controller/sdk.py b/api/controller/sdk.py
index 4dd5c3b..dac9388 100644
--- a/api/controller/sdk.py
+++ b/api/controller/sdk.py
@@ -117,7 +117,7 @@
 def Clean(input_proto, _output_proto, _config):
   """Clean unneeded files from a chroot."""
   chroot = controller_util.ParseChroot(input_proto.chroot)
-  sdk.Clean(chroot, sysroots=True, tmp=True)
+  sdk.Clean(chroot, images=True, sysroots=True, tmp=True)
 
 
 @faux.all_empty