lint: enable intrange linter (#7331)

Enable intrange linter to enforce modern Go range syntax over
traditional for loops, by converting:

for i := 0; i < n; i++

to:

for i := range n

Adding type conversions where needed for compatibility
with existing uint64 parameters.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

plugin/kubernetes/xfr.go

@@ -259,7 +259,7 @@ func emitAddressRecord(c chan<- []dns.RR, s msg.Service) string {
 func calcSRVWeight(numservices int) uint16 {
 	var services []msg.Service
 
-	for i := 0; i < numservices; i++ {
+	for range numservices {
 		services = append(services, msg.Service{})
 	}