add golangci-lint linter (#5499)

plugin/etcd/msg/service.go

@@ -154,7 +154,6 @@ func split255(s string) []string {
 		} else {
 			sx = append(sx, s[p:])
 			break
-
 		}
 		p, i = p+255, i+255
 	}

plugin/etcd/msg/type.go

@@ -15,11 +15,9 @@ import (
 //
 // Note that a service can double/triple as a TXT record or MX record.
 func (s *Service) HostType() (what uint16, normalized net.IP) {
-
 	ip := net.ParseIP(s.Host)
 
 	switch {
-
 	case ip == nil:
 		if len(s.Text) == 0 {
 			return dns.TypeCNAME, nil