Loadtesting db size (#9152)

* Allow for customizable DB instance type loadtesting

infrastructure/loadtesting/terraform/rds.tf

@@ -27,8 +27,8 @@ module "aurora_mysql" { #tfsec:ignore:aws-rds-enable-performance-insights-encryp
   name                  = "${local.name}-mysql"
   engine                = "aurora-mysql"
   engine_version        = "5.7.mysql_aurora.2.10.2"
-  instance_type         = "db.r6g.4xlarge"
-  instance_type_replica = "db.r6g.4xlarge"
+  instance_type         = var.db_instance_type
+  instance_type_replica = var.db_instance_type
 
   iam_database_authentication_enabled = true
   storage_encrypted                   = true

infrastructure/loadtesting/terraform/variables.tf

@@ -19,3 +19,9 @@ variable "loadtest_containers" {
   type        = number
   default     = 0
 }
+
+variable "db_instance_type" {
+  description = "The type of the loadtesting db instances.  Default is db.r6g.4xlarge."
+  type        = string
+  default     = "db.r6g.4xlarge"
+}