Move GardeningServer out of BuildSlaveSupport

Tools/GardeningServer/scripts/LayoutTestHistoryAnalyzer.js

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 160 matching lines @@
             const minimumRequiredTestRunsWithoutInterestingChanges = 5;
             callback(unexplainedFailuresCount || self._testRunsSinceLastInterestingChange < minimumRequiredTestRunsWithoutInterestingChanges);
         },
         function(tests) {
             // Some tests failed, but we couldn't fetch results.html (perhaps because the test
             // run aborted early for some reason). Just skip this build entirely.
             callback(true);
         });
     },
 };