Populate EtcdConfig in runtime from datastore when etcd is disabled (#5222)

Fixes issue with secrets-encrypt rotate not having any etcd endpoints
available on nodes without a local etcd server.

Signed-off-by: Brad Davidson <brad.davidson@rancher.com>

pkg/cluster/cluster.go

@@ -63,6 +63,9 @@ func (c *Cluster) Start(ctx context.Context) (<-chan struct{}, error) {
 			logrus.Warnf("Failed to remove this node from etcd members")
 		}
 
+		c.config.Runtime.EtcdConfig.Endpoints = strings.Split(c.config.Datastore.Endpoint, ",")
+		c.config.Runtime.EtcdConfig.TLSConfig = c.config.Datastore.BackendTLSConfig
+
 		return ready, nil
 	}