Update Patroni Runbooks to `node_list` TF method, after `node_count` deprecation

As we are moving the Patroni TF configuration from a node_count to a node_list https://ops.gitlab.net/gitlab-com/gl-infra/terraform-modules/google/generic-stor-with-group/-/merge_requests/39, we need to check the https://gitlab.com/gitlab-com/runbooks/-/tree/master/docs/patroni runbooks that make reference to node_count and update them to reflect this new configuration method

1. https://gitlab.com/gitlab-com/runbooks/-/blob/master/docs/patroni/scale-down-patroni.md
2. https://gitlab.com/gitlab-com/runbooks/-/blob/master/docs/patroni/scale-up-patroni.md