Update Icing protos from piper upstream.

Change-Id: If0117363362baedc564e4c128b6d0a1009ace9b4
diff --git a/METADATA b/METADATA
index 54818bf..2af1aa1 100644
--- a/METADATA
+++ b/METADATA
@@ -12,6 +12,6 @@
     type: PIPER
     value: "http://google3/third_party/icing/"
   }
-  last_upgrade_date { year: 2019 month: 10 day: 31 }
+  last_upgrade_date { year: 2019 month: 11 day: 25 }
   license_type: NOTICE
 }