feat: Drop random pets from Managed Node Groups (#1372)

BREAKING CHANGES: We now decided to remove `random_pet` resources in Managed Node Groups (MNG). Those were used to recreate MNG if something change and also simulate the newly added argument `node_group_name_prefix`. But they were causing a lot of troubles. To upgrade the module without recreating your MNG, you will need to explicitly reuse their previous name and set them in your MNG `name` argument. Please see [upgrade docs](https://github.com/terraform-aws-modules/terraform-aws-eks/blob/master/docs/upgrades.md#upgrade-module-to-v1700-for-managed-node-groups) for more details.

modules/node_groups/locals.tf

@@ -25,4 +25,14 @@ locals {
     var.node_groups_defaults,
     v,
   ) if var.create_eks }
+
+  node_groups_names = { for k, v in local.node_groups_expanded : k => lookup(
+    v,
+    "name",
+    lookup(
+      v,
+      "name_prefix",
+      join("-", [var.cluster_name, k])
+    )
+  ) }
 }