SGComps: remove custom merge semantics for SGInputLoader

Gaudi v36r4 automatically handles the merge semantics of sets correctly.
The "Load" property is of type `DataObjIDColl`, which is an
`unordered_set` and thus we no longer need to define our own merge
semantics for it.

Control/SGComps/python/SGInputLoaderConfig.py

 #
-# Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
+# Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
 #
 from AthenaConfiguration.ComponentAccumulator import ComponentAccumulator
 from AthenaConfiguration.ComponentFactory import CompFactory
 
 def SGInputLoaderCfg(flags, **kwargs):
     sgil = CompFactory.SGInputLoader(**kwargs)
-
-    # Custom merge semantics to allow appending items to the Load list
-    def merge_sgil_types(a, b):
-        for item in b:
-            if item not in a:
-                a.append(item)
-        return a
-    sgil._descriptors['Load'].semantics.merge = merge_sgil_types
-
     acc = ComponentAccumulator()
     acc.addEventAlgo(sgil, primary=True)
     return acc