test(test_router_caching.py): remove unstable test

test would fail due to timing issues

litellm/tests/test_router_caching.py

@@ -264,32 +264,3 @@ async def test_acompletion_caching_on_router_caching_groups():
     except Exception as e:
         traceback.print_exc()
         pytest.fail(f"Error occurred: {e}")
-
-def test_rpm_limiting():
-    try:
-        litellm.set_verbose = True
-        model_list = [
-            {
-                "model_name": "gpt-3.5-turbo",
-                "litellm_params": {
-                    "model": "gpt-3.5-turbo",
-                    "api_key": os.getenv("OPENAI_API_KEY"),
-                },
-                "tpm": 10000,
-                "rpm": 3,
-            },
-        ]
-        
-        router = Router(
-                    model_list = model_list, 
-                    routing_strategy = "usage-based-routing",
-                )
-        failedCount = 0
-        for i in range(10):
-            try:
-                response = router.completion(model="gpt-3.5-turbo", messages=[{"role": "user", "content": ""}])
-            except ValueError as e:
-                failedCount += 1
-        assert failedCount == 7
-    except Exception as e:
-        pytest.fail(f"An exception occurred - {str(e)}")