Milo: Add task expired as a failure status

common/proto/milo/annotations.proto

 // Copyright (c) 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 syntax = "proto3";
 
 package milo;
 
 import "google/protobuf/timestamp.proto";
 
@@ skipping 19 matching lines @@
     EXCEPTION = 1;
     // The failure is related to a failed infrastructure component, not an error
     // with the Step itself.
     INFRA = 2;
     // The failure is due to a failed Dungeon Master dependency. This should be
     // used if a Step's external depdendency fails and the Step cannot recover
     // or proceed without it.
     DM_DEPENDENCY_FAILED = 3;
     // The step was cancelled.
     CANCELLED = 4;
+    // The failure was due to an resource exhausion. The step was scheduled
+    // but never ran, and never will run.
+    EXPIRED = 5;
   }
   Type type = 1;
 
   // An optional string describing the failure.
   string text = 2;
 
   // If the failure type is DEPENDENCY_FAILED, the failed dependencies should be
   // listed here.
   repeated DMLink failed_dm_dependency = 3;
 }
@@ skipping 136 matching lines @@
 
   // The quest name.
   string quest = 2;
 
   // The attempt number.
   int64 attempt = 3;
 
   // The execution number.
   int64 execution = 4;
 }