tgc-revival: fix alloydb cluster tests (#15612)

Author: zli82016

mmv1/products/alloydb/Cluster.yaml

@@ -60,6 +60,7 @@ custom_code:
   pre_update: 'templates/terraform/pre_update/alloydb_cluster.go.tmpl'
   pre_delete: 'templates/terraform/pre_delete/alloydb_cluster.go.tmpl'
   constants: 'templates/terraform/constants/alloydb_cluster.go.tmpl'
+  tgc_decoder: 'templates/tgc_next/decoders/alloydb_cluster.go.tmpl'
 custom_diff:
   - 'alloydbClusterCustomizeDiff'
 # Skipping the sweeper because we need to force-delete clusters.

mmv1/templates/tgc_next/decoders/alloydb_cluster.go.tmpl

@@ -0,0 +1,8 @@
+// password is missing in CAI asset, but password is required in Terraform
+if res["initialUser"] == nil && res["clusterType"] == "PRIMARY" {
+    res["initialUser"] = map[string]interface{}{
+        "password": "hidden",
+    }
+}
+
+return res, hclData, nil