Replace uses of code which requires 1.24+

Signed-off-by: Derek McGowan <derek@mcg.dev>

integration/network/bridge/bridge_linux_test.go

@@ -889,7 +889,9 @@ func TestFirewallBackendSwitch(t *testing.T) {
 			dump = icmd.RunCommand("iptables-save").Combined()
 			dump += icmd.RunCommand("ip6tables-save").Combined()
 		})
-		for line := range strings.Lines(dump) {
+
+		// TODO: (When Go 1.24 is min version) Replace with `strings.Lines(dump)`.
+		for _, line := range strings.Split(dump, "\n") {
 			line = strings.TrimSpace(line)
 			if line == "" {
 				continue

integration/network/bridge/nftablesdoc/nftablesdoc_linux_test.go

@@ -20,6 +20,7 @@ package nftablesdoc
 import (
 	"context"
 	"fmt"
+	"iter"
 	"net/netip"
 	"os"
 	"path/filepath"
@@ -413,7 +414,7 @@ func runNftables(t *testing.T, host networking.Host) map[string]string {
 	//     {{index . "map filter-forward-out-jumps"}}
 
 	var sb strings.Builder
-	for line := range strings.Lines(out) {
+	for line := range lines(out) {
 		if line == "\n" || (line != "" && line[0] == '}') {
 			block := sb.String()
 			sb.Reset()
@@ -428,6 +429,24 @@ func runNftables(t *testing.T, host networking.Host) map[string]string {
 	return res
 }
 
+// lines produces a line iterator
+// TODO: (When Go 1.24 is min version) Replace with `strings.Lines(out)`.
+func lines(s string) iter.Seq[string] {
+	return func(yield func(string) bool) {
+		for s != "" {
+			var line string
+			if i := strings.IndexByte(s, '\n'); i >= 0 {
+				line, s = s[:i+1], s[i+1:]
+			} else {
+				line, s = s, ""
+			}
+			if !yield(line) {
+				return
+			}
+		}
+	}
+}
+
 func generate(t *testing.T, name string, data map[string]string) string {
 	t.Helper()
 	templ, err := template.New(name).ParseFiles(filepath.Join("templates", name))