cmd/tailscale/cli: use new Go 1.23 slices.Sorted

And a grammatical nit.

Updates #12912

Change-Id: I9feae53beb4d28dfe98b583373e2e0a43c801fc4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/dns-status.go

@@ -6,6 +6,7 @@ package cli
 import (
 	"context"
 	"fmt"
+	"maps"
 	"slices"
 	"strings"
 
@@ -76,12 +77,7 @@ func runDNSStatus(ctx context.Context, args []string) error {
 	if len(dnsConfig.Routes) == 0 {
 		fmt.Println("  (no routes configured: split DNS might not be in use)")
 	}
-	routesKeys := make([]string, 0, len(dnsConfig.Routes))
-	for k := range dnsConfig.Routes {
-		routesKeys = append(routesKeys, k)
-	}
-	slices.Sort(routesKeys)
-	for _, k := range routesKeys {
+	for _, k := range slices.Sorted(maps.Keys(dnsConfig.Routes)) {
 		v := dnsConfig.Routes[k]
 		for _, r := range v {
 			fmt.Printf("  - %-30s -> %v", k, r.Addr)