-Remove service.py usages in builder

-Raise warnings for deprecated google/protobuf/service.py APIs.

service.py APIs are marked as deprecated since 2010. These APIs will be
removed in Jan 2025

PiperOrigin-RevId: 653280370

python/google/protobuf/internal/builder.py

@@ -105,12 +105,11 @@ def BuildServices(file_des, module_name, module):
     module: Generated _pb2 module
   """
   # pylint: disable=g-import-not-at-top
-  from google.protobuf import service as _service
   from google.protobuf import service_reflection
   # pylint: enable=g-import-not-at-top
   for (name, service) in file_des.services_by_name.items():
     module[name] = service_reflection.GeneratedServiceType(
-        name, (_service.Service,),
+        name, (),
         dict(DESCRIPTOR=service, __module__=module_name))
     stub_name = name + '_Stub'
     module[stub_name] = service_reflection.GeneratedServiceStubType(

python/google/protobuf/service.py

@@ -19,6 +19,14 @@ and can avoid unnecessary layers of indirection.
 
 __author__ = 'petar@google.com (Petar Petrov)'
 
+import warnings
+
+warnings.warn(
+    'google.protobuf.service module is deprecated. RPC implementations '
+    'should provide code generator plugins which generate code specific to '
+    'the RPC implementation. service.py will be removed in Jan 2025',
+    stacklevel=2,
+)
 
 class RpcException(Exception):
   """Exception raised on failed blocking RPC method call."""