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/file/dnssec_test.go

@@ -169,7 +169,7 @@ func BenchmarkFileLookupDNSSEC(b *testing.B) {
 
 	b.ResetTimer()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		fm.ServeDNS(ctx, rec, m)
 	}
 }

plugin/file/file_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func BenchmarkFileParseInsert(b *testing.B) {
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		Parse(strings.NewReader(dbMiekENTNL), testzone, "stdin", 0)
 	}
 }

plugin/file/lookup_test.go

@@ -318,7 +318,7 @@ func BenchmarkFileLookup(b *testing.B) {
 
 	b.ResetTimer()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		fm.ServeDNS(ctx, rec, m)
 	}
 }

plugin/file/tree/less_test.go

@@ -63,7 +63,7 @@ Tests:
 		}
 
 		sort.Sort(set(test.in))
-		for i := 0; i < len(test.in); i++ {
+		for i := range len(test.in) {
 			if test.in[i] != test.out[i] {
 				t.Errorf("Test %d: expected %s, got %s", j, test.out[i], test.in[i])
 				n := ""