telemetry initialization and enhance event handling (#2853)

* Refactor Crew class memory initialization and enhance event handling

- Simplified the initialization of the external memory attribute in the Crew class.
- Updated memory system retrieval logic for consistency in key usage.
- Introduced a singleton pattern for the Telemetry class to ensure a single instance.
- Replaced telemetry usage in CrewEvaluator with event bus emissions for test results.
- Added new CrewTestResultEvent to handle crew test results more effectively.
- Updated event listener to process CrewTestResultEvent and log telemetry data accordingly.
- Enhanced tests to validate the singleton pattern in Telemetry and the new event handling logic.

* linted

* Remove unused telemetry attribute from Crew class memory initialization

* fix ordering of test

* Implement thread-safe singleton pattern in Telemetry class

- Introduced a threading lock to ensure safe instantiation of the Telemetry singleton.
- Updated the __new__ method to utilize double-checked locking for instance creation.

src/crewai/utilities/events/crew_events.py

@@ -100,3 +100,12 @@ class CrewTestFailedEvent(CrewBaseEvent):
 
     error: str
     type: str = "crew_test_failed"
+
+
+class CrewTestResultEvent(CrewBaseEvent):
+    """Event emitted when a crew test result is available"""
+
+    quality: float
+    execution_duration: float
+    model: str
+    type: str = "crew_test_result"

src/crewai/utilities/events/event_listener.py

@@ -37,6 +37,7 @@ from .crew_events import (
     CrewKickoffStartedEvent,
     CrewTestCompletedEvent,
     CrewTestFailedEvent,
+    CrewTestResultEvent,
     CrewTestStartedEvent,
     CrewTrainCompletedEvent,
     CrewTrainFailedEvent,
@@ -134,6 +135,15 @@ class EventListener(BaseEventListener):
         def on_crew_train_failed(source, event: CrewTrainFailedEvent):
             self.formatter.handle_crew_train_failed(event.crew_name or "Crew")
 
+        @crewai_event_bus.on(CrewTestResultEvent)
+        def on_crew_test_result(source, event: CrewTestResultEvent):
+            self._telemetry.individual_test_result_span(
+                source.crew,
+                event.quality,
+                int(event.execution_duration),
+                event.model,
+            )
+
         # ----------- TASK EVENTS -----------
 
         @crewai_event_bus.on(TaskStartedEvent)