chore(metadata): add vpc_service_control_attach_dry_run (#905)

Co-authored-by: Andrew Peabody <andrewpeabody@google.com>

Author: eeaton

metadata.yaml

@@ -334,7 +334,12 @@ spec:
     default: ""
     required: false
   - name: vpc_service_control_attach_enabled
-    description: Whether the project will be attached to a VPC Service Control Perimeter
+    description: Whether the project will be attached to a VPC Service Control Perimeter in ENFORCED MODE. vpc_service_control_attach_dry_run should be false for this to be true
+    type: bool
+    default: false
+    required: false
+  - name: vpc_service_control_attach_dry_run
+    description: Whether the project will be attached to a VPC Service Control Perimeter in Dry Run Mode. vpc_service_control_attach_enabled should be false for this to be true
     type: bool
     default: false
     required: false