refactor(load-snapshot): build LoadSnapshot directly, drop legacy get_loads IPC (#30525)

Co-authored-by: cctry <cctry@fb.com>

test/registered/utils/test_type_based_dispatcher.py

@@ -34,7 +34,6 @@ class TestTypeBasedDispatcher(unittest.TestCase):
             FlushCacheReqInput,
             FreezeGCReq,
             GetInternalStateReq,
-            GetLoadsReqInput,
             GetWeightsByNameReqInput,
             InitWeightsSendGroupForRemoteInstanceReqInput,
             InitWeightsUpdateGroupReqInput,
@@ -114,7 +113,6 @@ class TestTypeBasedDispatcher(unittest.TestCase):
             (ExpertDistributionReq, lambda req: "expert_distribution_handled"),
             (LoadLoRAAdapterReqInput, lambda req: "load_lora_adapter_handled"),
             (UnloadLoRAAdapterReqInput, lambda req: "unload_lora_adapter_handled"),
-            (GetLoadsReqInput, lambda req: "get_loads_handled"),
         ]
 
         # Create requests that conforms to the real distribution
@@ -209,7 +207,6 @@ class TestTypeBasedDispatcher(unittest.TestCase):
         test_requests.append(GetWeightsByNameReqInput(name=""))
         test_requests.append(ReleaseMemoryOccupationReqInput())
         test_requests.append(RpcReqInput(method=""))
-        test_requests.append(GetLoadsReqInput())
 
         dispatcher = TypeBasedDispatcher(mapping)