…fault is disabled

* disables aws_lb_listener.http_forward when default_target_group is not enabled
* target_group is required when type is 'redirect'

Fixes this Validation error when default_target_group_enabled == 0 :

```
module.alb.aws_lb_listener.http_forward[0]: Creating...
╷
│ Error: creating ELBv2 Listener
(arn:aws:elasticloadbalancing:...:...:loadbalancer/...):
ValidationError: A target group ARN must be specified
│       status code: 400, request id:
7cf9d727-fc77-4d32-a160-cbd175e16e20
│
│   with module.alb.aws_lb_listener.http_forward[0],
│   on .terraform/modules/alb/main.tf line 150, in resource
"aws_lb_listener" "http_forward":
│  150: resource "aws_lb_listener" "http_forward" {

```

…sabled

…sabled

…sabled