Use user CAs in checkEndpoint() call (#8911)

The server info handler makes a http connection to other
nodes to check if they are up but does not load the custom
CAs in ~/.minio/certs/CAs.

This commit fix it.

Co-authored-by: Harshavardhana <harsha@minio.io>

pkg/net/url.go

@@ -86,14 +86,20 @@ func (u *URL) UnmarshalJSON(data []byte) (err error) {
 }
 
 // DialHTTP - dials the url to check the connection.
-func (u URL) DialHTTP() error {
-	var client = &http.Client{
-		Transport: &http.Transport{
+func (u URL) DialHTTP(transport *http.Transport) error {
+	if transport == nil {
+		transport = &http.Transport{
 			DialContext: (&net.Dialer{
 				Timeout: 2 * time.Second,
 			}).DialContext,
-		},
+		}
+
 	}
+
+	var client = &http.Client{
+		Transport: transport,
+	}
+
 	req, err := http.NewRequest("POST", u.String(), nil)
 	if err != nil {
 		return err