In [this PR](https://github.com/localstack/localstack/pull/1200/files) we introduced a new way of starting S3 in a separate process.

In the meantime, the service startup has been significantly reworked, and it seems that we can integrate the S3 starter into the [`multiserver.py`](https://github.com/localstack/localstack/blob/master/localstack/utils/server/multiserver.py) based loading approach that loads multiple APIs in a single process, for performance reasons. We should look into that.
cf_update_stack_orig = cf_backend.update_stack
        def cf_update_stack(self, *args, **kwargs):
            stack = cf_update_stack_orig(*args, **kwargs)
            
            self._validate_export_uniqueness(stack)
            for export in stack.exports:
                self.exports[export.name] = export
            return stack
        return types.MethodType(cf_update_stack, cf_backend)
    for region, cf_backend in cloudformation_backends.items():
        cf_backend.update_stack = make_cf_update_stack(cf_backend)
    
    def DynamoDB_Table_get_cfn_attribute(self, attribute_name):