kubeadm-config.v1beta2.yaml.j2: etcd log level arg (#7339)

According to [etcd's docs](https://etcd.io/docs/v3.4.0/op-guide/configuration/#--log-package-levels), argument 'log-package-levels' should not contain underscores.

roles/kubernetes/control-plane/templates/kubeadm-config.v1beta2.yaml.j2

@@ -59,7 +59,7 @@ etcd:
       quota-backend-bytes: "{{ etcd_quota_backend_bytes }}"
 {% endif %}
 {% if etcd_log_package_levels is defined %}
-      log-package_levels: "{{ etcd_log_package_levels }}"
+      log-package-levels: "{{ etcd_log_package_levels }}"
 {% endif %}
 {% for key, value in etcd_extra_vars.items() %}
       {{ key }}: "{{ value }}"