Fix create_[secure/insecure]_channel argument order

src/python/grpcio/grpc/__init__.py

@@ -1059,7 +1059,7 @@ def insecure_channel(target, options=None):
     A Channel to the target through which RPCs may be conducted.
   """
   from grpc import _channel
-  return _channel.Channel(target, None, options)
+  return _channel.Channel(target, options, None)
 
 
 def secure_channel(target, credentials, options=None):
@@ -1075,7 +1075,7 @@ def secure_channel(target, credentials, options=None):
     A Channel to the target through which RPCs may be conducted.
   """
   from grpc import _channel
-  return _channel.Channel(target, credentials, options)
+  return _channel.Channel(target, options, credentials)
 
 
 def server(generic_rpc_handlers, thread_pool, options=None):

src/python/grpcio/tests/unit/beta/test_utilities.py

@@ -50,6 +50,6 @@ def not_really_secure_channel(
   """
   target = '%s:%d' % (host, port)
   channel = grpc.secure_channel(
-      target, ((b'grpc.ssl_target_name_override', server_host_override,),),
+      target, channel_credentials._credentials,
-      channel_credentials._credentials)
+      ((b'grpc.ssl_target_name_override', server_host_override,),))
   return implementations.Channel(channel)