replacing + adding a sg to lb causes an error

[vburckhardt]

Steps to reproduce:

1. set additional_lb_security_group_ids to an array with one sg
2. apply
3. set additional_lb_security_group_ids to an array with an additional sg (ensure you append the additional sg as element 0 of the array)
4. apply

Error:

╷
│ Error: Invalid index
│ 
│   on ../../main.tf line 615, in resource "null_resource" "confirm_lb_active":
│  615:     command     = "${path.module}/scripts/confirm_lb_active.sh ${var.region} ${local.lbs_associated_with_cluster[count.index]} ${var.use_private_endpoint}"
│     ├────────────────
│     │ count.index is 1
│     │ local.lbs_associated_with_cluster is list of string with 1 element
│ 
│ The given key does not identify an element in this collection value: the given index is greater than or equal to the length of the collection.