feat: create new dataset classic-gcd (based on dataset classic) to enable deployment on GCD (#3679)

* feat: create classic dataset for GCD deployments

* Revert billing config to classic

* Revert GCD README

* Restore billing project in GCD

* Add basic alignment-test with classic dataset

---------

Co-authored-by: Julio Castillo <jccb@google.com>

tools/duplicate-diff.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-# Copyright 2025 Google LLC
+# Copyright 2026 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -24,12 +24,22 @@ duplicates = [
     # deep recursive folder comparison
     [
         "fast/stages/0-org-setup/datasets/classic/organization/custom-roles",
+        "fast/stages/0-org-setup/datasets/classic-gcd/organization/custom-roles",
         "fast/stages/0-org-setup/datasets/hardened/organization/custom-roles",
     ],
     [
         "fast/stages/0-org-setup/datasets/classic/organization/tags",
+        "fast/stages/0-org-setup/datasets/classic-gcd/organization/tags",
         "fast/stages/0-org-setup/datasets/hardened/organization/tags",
     ],
+    [
+        "fast/stages/0-org-setup/datasets/classic/billing-accounts",
+        "fast/stages/0-org-setup/datasets/classic-gcd/billing-accounts",
+    ],
+    [
+        "fast/stages/0-org-setup/datasets/classic/folders",
+        "fast/stages/0-org-setup/datasets/classic-gcd/folders",
+    ],
     # schemas
     [
         "fast/stages/1-vpcsc/schemas/access-level.schema.json",