Add timeout to Azure ACR credential provider

Adds a default timeout to the Azure ACR HTTP client to avoid hanging
when unable to reach server.

Signed-off-by: hasheddan <georgedanielmangum@gmail.com>

pkg/credentialprovider/azure/azure_acr_helper.go

@@ -57,7 +57,10 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+	"time"
 	"unicode"
+
+	utilnet "k8s.io/apimachinery/pkg/util/net"
 )
 
 type authDirective struct {
@@ -75,7 +78,10 @@ const userAgent = "kubernetes-credentialprovider-acr"
 
 const dockerTokenLoginUsernameGUID = "00000000-0000-0000-0000-000000000000"
 
-var client = &http.Client{}
+var client = &http.Client{
+	Transport: utilnet.SetTransportDefaults(&http.Transport{}),
+	Timeout:   time.Second * 10,
+}
 
 func receiveChallengeFromLoginServer(serverAddress string) (*authDirective, error) {
 	challengeURL := url.URL{