Remove hard-coded externaldns image versions

Related story: https://mirantis.jira.com/browse/PROD-22456

Change-Id: I7a0eb61cfc85ac71adc287bb9ee33e8c47cf9e97
diff --git a/classes/cluster/sl-k8s-calico/kubernetes/init.yml b/classes/cluster/sl-k8s-calico/kubernetes/init.yml
index 2560ec8..6b5fa3a 100644
--- a/classes/cluster/sl-k8s-calico/kubernetes/init.yml
+++ b/classes/cluster/sl-k8s-calico/kubernetes/init.yml
@@ -31,7 +31,7 @@
 
     kubernetes_criproxy_version: v0.11.0
     kubernetes_criproxy_checksum: md5=115bbb0c27518db6b0b3bc8cdc5fc897
-    kubernetes_externaldns_image: mirantis/external-dns:latest
+
     kubernetes_externaldns_provider: coredns
     kubernetes_metallb_addresses_pool: 172.16.10.60-172.16.10.80