refact(enos): Increase clarity in module variable name

This variable defines the IP address of a target used in tests. We should pass in the address itself instead of a list of addresses that will get converted to a single address eventually anyways.

enos/enos-scenario-e2e-credential-vault.hcl

@@ -131,7 +131,7 @@ scenario "e2e_credential_vault" {
       auth_password            = step.create_boundary_cluster.auth_password
       local_boundary_dir       = local.local_boundary_dir
       aws_ssh_private_key_path = local.aws_ssh_private_key_path
-      target_ips               = step.create_target.target_ips
+      target_ip                = step.create_target.target_ips[0]
       target_user              = "ubuntu"
       vault_addr               = step.create_vault_cluster.instance_public_ips[0]
       vault_root_token         = step.create_vault_cluster.vault_root_token

enos/enos-scenario-e2e-host-static.hcl

@@ -108,7 +108,7 @@ scenario "e2e_host_static" {
       auth_password            = step.create_boundary_cluster.auth_password
       local_boundary_dir       = local.local_boundary_dir
       aws_ssh_private_key_path = local.aws_ssh_private_key_path
-      target_ips               = step.create_target.target_ips
+      target_ip                = step.create_target.target_ips[0]
       target_user              = "ubuntu"
     }
   }

enos/modules/test_e2e/main.tf

@@ -38,10 +38,10 @@ variable "aws_ssh_private_key_path" {
   description = "Local Path to key used to SSH onto created hosts"
   type        = string
 }
-variable "target_ips" {
-  description = "List of IP Addresses of created hosts"
-  type        = list(string)
-  default     = [""]
+variable "target_ip" {
+  description = "IP address of target"
+  type        = string
+  default     = ""
 }
 variable "vault_addr" {
   description = "URL of Vault instance"
@@ -101,7 +101,7 @@ resource "enos_local_exec" "run_e2e_test" {
     E2E_PASSWORD_AUTH_METHOD_ID   = var.auth_method_id,
     E2E_PASSWORD_ADMIN_LOGIN_NAME = var.auth_login_name,
     E2E_PASSWORD_ADMIN_PASSWORD   = var.auth_password,
-    E2E_TARGET_IP                 = var.target_ips[0],
+    E2E_TARGET_IP                 = var.target_ip,
     E2E_SSH_USER                  = var.target_user,
     E2E_SSH_KEY_PATH              = local.aws_ssh_private_key_path,
     VAULT_ADDR                    = local.vault_addr,