[Master][bug]utils.LocalIp sometimes is a looback ip

[ZhouJunjun]

Sometimes value of utils.LocalIp is a loopback ip, cause in line 48:!ipnet.IP.IsLoopback() is only hit ip like 127.* or ::1
If some of server's net interface is a loopback interface, value of utils.LocalIp might be a loopback ip(which is not like 127.*)

https://github.com/apache/rocketmq-client-go/blob/master/internal/utils/net.go#L29-L54

so i think ClientIP4() should filter lookback interface first like this:

func GetLocalServerIp() (string, error) {
    if ifaceSlice, err := net.Interfaces(); err == nil && ifaceSlice != nil {
        for _, iface := range ifaceSlice {
            if iface.Flags&net.FlagLoopback != 0 {
                continue // loopback interface
            }
            if iface.Flags&net.FlagUp == 0 {
                continue // interface down
            }
            
            if tmpAddrSlice, err := iface.Addrs(); err == nil && tmpAddrSlice != nil {
                for _, address := range tmpAddrSlice {
                    if ipNet, ok := address.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
                        if ipNet.IP.To4() != nil {
                            return ipNet.IP.String(), nil
                        }
                    }
                }
            }
        }
    }
    return "", fmt.Errorf("ip not found")
}

[ShannonDing]

a PR is welcomed and it will be review asap.