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/evaluators/crew_evaluator_handler.py

@@ -9,7 +9,8 @@ from crewai.agent import Agent
 from crewai.llm import BaseLLM
 from crewai.task import Task
 from crewai.tasks.task_output import TaskOutput
-from crewai.telemetry import Telemetry
+from crewai.utilities.events import crewai_event_bus
+from crewai.utilities.events.crew_events import CrewTestResultEvent
 
 
 class TaskEvaluationPydanticOutput(BaseModel):
@@ -36,7 +37,6 @@ class CrewEvaluator:
     def __init__(self, crew, eval_llm: InstanceOf[BaseLLM]):
         self.crew = crew
         self.llm = eval_llm
-        self._telemetry = Telemetry()
         self._setup_for_evaluating()
 
     def _setup_for_evaluating(self) -> None:
@@ -178,11 +178,15 @@ class CrewEvaluator:
         evaluation_result = evaluation_task.execute_sync()
 
         if isinstance(evaluation_result.pydantic, TaskEvaluationPydanticOutput):
-            self._test_result_span = self._telemetry.individual_test_result_span(
+            crewai_event_bus.emit(
                 self.crew,
-                evaluation_result.pydantic.quality,
-                current_task.execution_duration,
-                self.llm.model,
+                CrewTestResultEvent(
+                    quality=evaluation_result.pydantic.quality,
+                    execution_duration=current_task.execution_duration,
+                    model=self.llm.model,
+                    crew_name=self.crew.name,
+                    crew=self.crew,
+                ),
             )
             self.tasks_scores[self.iteration].append(evaluation_result.pydantic.quality)
             self.run_execution_times[self.iteration].append(