Adding test case reproducibility metric (#4358)

### Motivation

The Chrome team has no easy visibility into how many manually uploaded
test cases flake or successfully reproduce. This PR implements a counter
metric to track that.

There are three possible outcomes, each represented by a string label:
'reproduces', 'one_timer' and 'does_not_reproduce'

Part of #4271

src/clusterfuzz/_internal/bot/tasks/utasks/analyze_task.py

@@ -34,6 +34,7 @@
 from clusterfuzz._internal.datastore import data_types
 from clusterfuzz._internal.fuzzing import leak_blacklist
 from clusterfuzz._internal.metrics import logs
+from clusterfuzz._internal.metrics import monitoring_metrics
 from clusterfuzz._internal.protos import uworker_msg_pb2
 from clusterfuzz._internal.system import environment
 
@@ -409,6 +410,14 @@ def utask_main(uworker_input):
   analyze_task_output.crash_stacktrace = testcase.crash_stacktrace
 
   if not crashed:
+    monitoring_metrics.ANALYZE_TASK_REPRODUCIBILITY.increment(
+        labels={
+            'fuzzer_name': uworker_input.fuzzer_name,
+            'job': uworker_input.job_type,
+            'crashes': False,
+            'reproducible': False,
+            'platform': environment.platform(),
+        })
     return uworker_msg_pb2.Output(  # pylint: disable=no-member
         analyze_task_output=analyze_task_output,
         error_type=uworker_msg_pb2.ErrorType.ANALYZE_NO_CRASH,  # pylint: disable=no-member
@@ -425,7 +434,18 @@ def utask_main(uworker_input):
 
   test_for_reproducibility(fuzz_target, testcase, testcase_file_path, state,
                            test_timeout)
-  analyze_task_output.one_time_crasher_flag = testcase.one_time_crasher_flag
+  one_time_flag = testcase.one_time_crasher_flag
+
+  analyze_task_output.one_time_crasher_flag = one_time_flag
+
+  monitoring_metrics.ANALYZE_TASK_REPRODUCIBILITY.increment(
+      labels={
+          'fuzzer_name': uworker_input.fuzzer_name,
+          'job': uworker_input.job_type,
+          'crashes': True,
+          'reproducible': not one_time_flag,
+          'platform': environment.platform(),
+      })
 
   fuzz_target_metadata = engine_common.get_fuzz_target_issue_metadata(
       fuzz_target)

src/clusterfuzz/_internal/metrics/monitoring_metrics.py

@@ -250,3 +250,13 @@
         monitor.StringField('fuzzer_name'),
         monitor.StringField('status'),
     ])
+
+ANALYZE_TASK_REPRODUCIBILITY = monitor.CounterMetric(
+    'task/analyze/reproducibility',
+    description='Outcome count for analyze task.',
+    field_spec=[
+        monitor.StringField('job'),
+        monitor.StringField('fuzzer_name'),
+        monitor.BooleanField('reproducible'),
+        monitor.BooleanField('crashes'),
+    ])