Use `ipFamilyPolicy: RequireDualStack` for dual-stack kube-dns (#8984)

Signed-off-by: Aofei Sheng <aofei@aofeisheng.com>
(cherry picked from commit 8d2c40cdac)
Signed-off-by: Brad Davidson <brad.davidson@rancher.com>

pkg/server/server.go

@@ -274,9 +274,9 @@ func stageFiles(ctx context.Context, sc *Context, controlConfig *config.Control)
 	}
 	dataDir = filepath.Join(controlConfig.DataDir, "manifests")
 
-	dnsIPFamilyPolicy := "PreferDualStack"
+	dnsIPFamilyPolicy := "SingleStack"
-	if len(controlConfig.ClusterDNSs) == 1 {
+	if len(controlConfig.ClusterDNSs) > 1 {
-		dnsIPFamilyPolicy = "SingleStack"
+		dnsIPFamilyPolicy = "RequireDualStack"
 	}
 
 	templateVars := map[string]string{