[BUG] - Error deleting VPC2 when it is attached to bare metal or instance

[optik-aper]

Describe the bug
When VPC2s are attached to bare metals, the destroy doesn't follow the correct order or it times out since there is a process behind the scene that does the actual detaching.

To Reproduce

• Create some BM/Instance & VPC2 resource(s), attached

resource "vultr_vpc2" "foo" {
  region   = "mel"
  description = "foo"
  ip_type = "v4"
  ip_block = "10.10.0.0"
  prefix_length = 16
}

resource "vultr_vpc2" "bar" {
  region   = "mel"
  description = "bar"
  ip_type = "v4"
  ip_block = "10.11.0.0"
  prefix_length = 16
}

resource "vultr_bare_metal_server" "bmvpc" {
  os_id = 1743
  plan = "vbm-6c-32gb"
  region = "mel"
  label = "tf-vpc2-test"
  tags = ["tf", "test"]
  vpc2_ids = [vultr_vpc2.foo.id]
}

resource "vultr_instance" "instvpc" {
  region = "mel"
  plan = "vc2-2c-4gb"
  label = "tf-vpc2-test"
  os_id = 1743
  vpc2_ids = [vultr_vpc2.foo.id, vultr_vpc2.bar.id]
}

• Try to destroy them:

$ terraform destroy                                                                                                                                                           15:33

vultr_vpc2.bar: Refreshing state... [id=abd1a734-9f1a-4055-9c6f-3dd28ca7e51d]
data.vultr_instance.instance_list: Reading...
vultr_vpc2.foo: Refreshing state... [id=00104d0f-7473-42f9-8a4d-42085f9b062a]
vultr_bare_metal_server.bmvpc: Refreshing state... [id=8b8d846c-79a4-41c6-914c-0a59962deaa4]
vultr_instance.instvpc: Refreshing state... [id=1e436faf-eeed-4403-ae1a-4496e621504a]
data.vultr_instance.instance_list: Read complete after 7s [id=6059cec4-2b7e-4660-b2cf-eca62bef60e6]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  - destroy

Terraform will perform the following actions:

  # vultr_bare_metal_server.bmvpc will be destroyed
  - resource "vultr_bare_metal_server" "bmvpc" {
      - app_id          = 0 -> null
      - cpu_count       = 6 -> null
      - date_created    = "2023-09-05T19:58:34+00:00" -> null
      - disk            = "2x 960GB SSD" -> null
      - gateway_v4      = "67.219.104.1" -> null
      - id              = "8b8d846c-79a4-41c6-914c-0a59962deaa4" -> null
      - label           = "tf-vpc2-test" -> null
      - mac_address     = 66988331878112 -> null
      - main_ip         = "67.219.104.165" -> null
      - netmask_v4      = "255.255.254.0" -> null
      - os              = "Ubuntu 22.04 LTS x64" -> null
      - os_id           = 1743 -> null
      - plan            = "vbm-6c-32gb" -> null
      - ram             = "32768 MB" -> null
      - region          = "mel" -> null
      - status          = "active" -> null
      - tags            = [
          - "test",
          - "tf",
        ] -> null
      - v6_network_size = 0 -> null
      - vpc2_ids        = [
          - "00104d0f-7473-42f9-8a4d-42085f9b062a",
        ] -> null
    }

  # vultr_instance.instvpc will be destroyed
  - resource "vultr_instance" "instvpc" {
      - allowed_bandwidth   = 9 -> null
      - app_id              = 0 -> null
      - backups             = "disabled" -> null
      - date_created        = "2023-09-07T18:10:40+00:00" -> null
      - ddos_protection     = false -> null
      - default_password    = (sensitive value) -> null
      - disk                = 80 
      - features            = [] -> null
      - gateway_v4          = "67.219.98.1" -> null
      - hostname            = "vultr.guest" -> null
      - id                  = "1e436faf-eeed-4403-ae1a-4496e621504a" -> null
      - kvm                 = "https://my.vultr.com/subs/vps/novnc/api.php?data=djJ8UWhwbkM0d1lWWXFpTDk3N3BfbUZwQXVYTEk4QVdOSWN8X64wQlHqOMJ8AhjBFYVs8-1MeEr1fh2RNcZV93M8uIRY0XuZhJBHfXx1arPVGEsQ0TgsoqEP3nCO201EfSxvC7YV3Bu4D5Z2iWPTBVl-RytKVrmgS894lLD5ZRpMy159Pof0LYgcdQDmWMqq9D_tbqeo1ax28A9fbqaUIFdbj3BW4jisk2L5_XHj-Z_4GGfIa3Ij0qOkUWedKN1D7Q" -> null
      - label               = "tf-vpc2-test" -> null
      - main_ip             = "67.219.98.234" -> null
      - netmask_v4          = "255.255.254.0" -> null
      - os                  = "Ubuntu 22.04 x64" -> null
      - os_id               = 1743 -> null
      - plan                = "vc2-2c-4gb" -> null
      - power_status        = "running" -> null
      - private_network_ids = [] -> null
      - ram                 = 4096 -> null
      - region              = "mel" -> null
      - server_status       = "ok" -> null
      - status              = "active" -> null
      - tags                = [] -> null
      - v6_network_size     = 0 -> null
      - vcpu_count          = 2 -> null
      - vpc2_ids            = [
          - "00104d0f-7473-42f9-8a4d-42085f9b062a",
          - "abd1a734-9f1a-4055-9c6f-3dd28ca7e51d",
        ] -> null
      - vpc_ids             = [] -> null
    }

  # vultr_vpc2.bar will be destroyed
  - resource "vultr_vpc2" "bar" {
      - date_created  = "2023-09-06T18:56:21+00:00" -> null
      - description   = "bar" -> null
      - id            = "abd1a734-9f1a-4055-9c6f-3dd28ca7e51d" -> null
      - ip_block      = "10.11.0.0" -> null
      - ip_type       = "v4" -> null
      - prefix_length = 16 -> null
      - region        = "mel" -> null
    }

  # vultr_vpc2.foo will be destroyed
  - resource "vultr_vpc2" "foo" {
      - date_created  = "2023-09-06T18:52:29+00:00" -> null
      - description   = "foo" -> null
      - id            = "00104d0f-7473-42f9-8a4d-42085f9b062a" -> null
      - ip_block      = "10.10.0.0" -> null
      - ip_type       = "v4" -> null
      - prefix_length = 16 -> null
      - region        = "mel" -> null
    }

Plan: 0 to add, 0 to change, 4 to destroy.

Do you really want to destroy all resources?
  Terraform will destroy all your managed infrastructure, as shown above.
  There is no undo. Only 'yes' will be accepted to confirm.

  Enter a value: yes

vultr_bare_metal_server.bmvpc: Destroying... [id=8b8d846c-79a4-41c6-914c-0a59962deaa4]
vultr_instance.instvpc: Destroying... [id=1e436faf-eeed-4403-ae1a-4496e621504a]
vultr_instance.instvpc: Destruction complete after 4s
vultr_vpc2.bar: Destroying... [id=abd1a734-9f1a-4055-9c6f-3dd28ca7e51d]
╷
│ Error: error destroying VPC 2.0 (abd1a734-9f1a-4055-9c6f-3dd28ca7e51d): {"error":"The following servers are attached to this VPC 2.0 network: 67.219.98.234\n","status":400}
│
│
╵
╷
│ Error: error detaching VPCs 2.0 prior to deleting instance 8b8d846c-79a4-41c6-914c-0a59962deaa4 : {"error":"Invalid instance-id.","status":404}
│
│
╵

Expected behavior
Retries or waits until the VPC2 is detached before attempting to delete the VPC2

Additional context
#358 Might be a relevant example of this functionality