Run error-filtering script on diff-triggered tests

Summary:
this script creates a summary message based on the test type and
output. Previously it only ran during contbuild. This diff makes it also
run on commit-triggered diffs.

Test Plan: will see if it works on diff's sandcastle tests

Reviewers: kradhakrishnan, lightmark, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D60879

arcanist_util/config/RocksDBCommonHelper.php

@@ -134,6 +134,7 @@ function getSteps($applyDiff, $diffID, $username, $test) {
     "name" => "Run " . $test,
     "shell" => $cmd,
     "user" => "root",
+    "parser" => "python build_tools/error_filter.py " . $test,
   );
 
   $steps[] = $run_test;