LibSQL: Remove the now-unused ExecutionContext::result object

The INSERT and SELECT statements set up this object for any expression
evaluation to indicate errors. This is no longer needed.

Userland/Libraries/LibSQL/AST/Select.cpp

@@ -48,7 +48,6 @@ ResultOr<ResultSet> Select::execute(ExecutionContext& context) const
         }
     }
 
-    context.result = Result { SQLCommand::Select };
     ResultSet result { SQLCommand::Select };
 
     auto descriptor = adopt_ref(*new TupleDescriptor);