[harness-automation] save case failure times (#4261)

Save failure times for each case for judging if case passes randomly.

tools/harness-automation/autothreadharness/runner.py

@@ -106,10 +106,14 @@ class SimpleTestResult(unittest.TestResult):
             test (TestCase): The test just run
             passed (bool): Whether the case is passed
         """
+        fails = self.result.get(test.__class__.__name__, {}).get('fails', 0)
+        if passed is False:
+            fails += 1
         self.result[str(test.__class__.__name__)] = {
             'started': self.started,
             'stopped': time.strftime('%Y-%m-%dT%H:%M:%S'),
             'passed': passed,
+            'fails': fails,
             'error': error,
             'executions': SimpleTestResult.executions,
         }