Remove redundant ExchangeItem call

This was originally here to solve
https://gitlab.com/kicad/code/kicad/-/issues/17851 However, since then,
we have changed how pins are handled in UpdatePins(), leading to the
exchanged item having dangling pointers.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/21995

eeschema/dialogs/dialog_change_symbols.cpp

@@ -640,15 +640,6 @@ int DIALOG_CHANGE_SYMBOLS::processSymbols( SCH_COMMIT* aCommit, const std::map<S
         screen->Remove( symbol );
         SCH_SYMBOL* symbol_copy = static_cast<SCH_SYMBOL*>( symbol->Clone() );
         aCommit->Modified( symbol, symbol_copy, screen );
-
-        CONNECTION_GRAPH*           connectionGraph = screen->Schematic()->ConnectionGraph();
-
-        // When we replace the lib symbol below, we free the associated pins if the new symbol has
-        // fewer than the original.  This will cause the connection graph to be out of date unless
-        // we replace references in the graph to the old symbol/pins with references to the ones
-        // stored in the undo stack.
-        if( connectionGraph )
-            connectionGraph->ExchangeItem( symbol, symbol_copy );
     }
 
     for( const auto& [ symbol, symbol_change_info ] : symbols )