Fix trimmed labels being used in other metrics, due to shallow copy

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

@@ -83,6 +83,7 @@ def __init__(self, subtask: _Subtask):
     self.start_time_ns = time.time_ns()
     self._subtask = subtask
     self._labels = None
+    self._trimmed_labels = None
     self.utask_main_failure = None
     self._utask_success_conditions = [
         None,  # This can be a successful return value in, ie, fuzz task
@@ -177,10 +178,11 @@ def __exit__(self, _exc_type, _exc_value, _traceback):
     # Get rid of job as a label, so we can have another metric to make
     # error conditions more explicit, respecting the 30k distinct
     # labels limit recommended by gcp.
-    trimmed_labels = self._labels
+    trimmed_labels = {
+        **self._labels, 'task_succeeded': task_succeeded,
+        'error_condition': error_condition
+    }
     del trimmed_labels['job']
-    trimmed_labels['task_succeeded'] = task_succeeded
-    trimmed_labels['error_condition'] = error_condition
     monitoring_metrics.TASK_OUTCOME_COUNT_BY_ERROR_TYPE.increment(
         trimmed_labels)