(#CALM-40640) handle no auth in attrs in variable (nutanix#314)

### Summary
Quick fix for when variable attrs don't have auth.

(cherry picked from commit 7b9ff4b2f64a769e06b3c757ebd5638f521f4b2b)

calm/dsl/api/util.py

@@ -126,7 +126,9 @@ def strip_entity_secret_variables(
             opts = variable.get("options", None)
             auth = None
             if opts:
-                auth = opts["attrs"].get("authentication", None)
+                attrs = opts.get("attrs", None)
+                if attrs:
+                    auth = attrs.get("authentication", None)
             if auth and auth.get("auth_type") == "basic":
                 basic_auth = auth.get("basic_auth")
                 username = basic_auth.get("username")