Fix certificates checking when adding etcd node to existing k8s node (#5807) (#5826)

Co-authored-by: alexkomrakov <alexkomrakov@gmail.com>
(cherry picked from commit 6ad6609872)

roles/etcd/tasks/gen_certs_script.yml

@@ -55,7 +55,7 @@
   command: "bash -x {{ etcd_script_dir }}/make-ssl-etcd.sh -f {{ etcd_config_dir }}/openssl.conf -d {{ etcd_cert_dir }}"
   environment:
     - MASTERS: "{% for m in groups['etcd'] %}
-                  {% if gen_node_certs[m] %}
+                  {% if gen_master_certs[m] %}
                     {{ m }}
                   {% endif %}
                 {% endfor %}"