SdkController: Also clean the chroot's /tmp/.

BUG=None
TEST=run_tests

Change-Id: I5d1d922e5310b16f30eb67246f7a026e579f7fae
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2047546
Tested-by: Alex Klein <saklein@chromium.org>
Auto-Submit: Alex Klein <saklein@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Commit-Queue: Chris McDonald <cjmcdonald@chromium.org>
diff --git a/api/controller/sdk.py b/api/controller/sdk.py
index fbc7b8a..babdc93 100644
--- a/api/controller/sdk.py
+++ b/api/controller/sdk.py
@@ -110,4 +110,4 @@
 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)
+  sdk.Clean(chroot, sysroots=True, tmp=True)