chore!: deprecate eval/tasks (#1186)

# What does this PR do?
- Fully deprecate eval/tasks

[//]: # (If resolving an issue, uncomment and update the line below)
Closes #1088 

NOTE: this will be a breaking change. We have introduced the new API in
0.1.3 .

Notebook has been updated to use the new endpoints.

## Test Plan
```
pytest -v -s --nbval-lax ./docs/notebooks/Llama_Stack_Benchmark_Evals.ipynb 
```
<img width="611" alt="image"
src="https://github.com/user-attachments/assets/79f6efe1-81ba-494e-bf36-1fc0c2b9bc6f"
/>



cc @SLR722  for awareness

[//]: # (## Documentation)

llama_stack/apis/eval/eval.py

@@ -39,7 +39,6 @@ EvalCandidate = register_schema(
 
 @json_schema_type
 class BenchmarkConfig(BaseModel):
-    type: Literal["benchmark"] = "benchmark"
     eval_candidate: EvalCandidate
     scoring_params: Dict[str, ScoringFnParams] = Field(
         description="Map between scoring function id and parameters for each scoring function you want to run",
@@ -84,28 +83,3 @@ class Eval(Protocol):
 
     @webmethod(route="/eval/benchmarks/{benchmark_id}/jobs/{job_id}/result", method="GET")
     async def job_result(self, benchmark_id: str, job_id: str) -> EvaluateResponse: ...
-
-    @webmethod(route="/eval/tasks/{task_id}/jobs", method="POST")
-    async def DEPRECATED_run_eval(
-        self,
-        task_id: str,
-        task_config: BenchmarkConfig,
-    ) -> Job: ...
-
-    @webmethod(route="/eval/tasks/{task_id}/evaluations", method="POST")
-    async def DEPRECATED_evaluate_rows(
-        self,
-        task_id: str,
-        input_rows: List[Dict[str, Any]],
-        scoring_functions: List[str],
-        task_config: BenchmarkConfig,
-    ) -> EvaluateResponse: ...
-
-    @webmethod(route="/eval/tasks/{task_id}/jobs/{job_id}", method="GET")
-    async def DEPRECATED_job_status(self, task_id: str, job_id: str) -> Optional[JobStatus]: ...
-
-    @webmethod(route="/eval/tasks/{task_id}/jobs/{job_id}", method="DELETE")
-    async def DEPRECATED_job_cancel(self, task_id: str, job_id: str) -> None: ...
-
-    @webmethod(route="/eval/tasks/{task_id}/jobs/{job_id}/result", method="GET")
-    async def DEPRECATED_job_result(self, task_id: str, job_id: str) -> EvaluateResponse: ...