Handle non-existant plan when getting deployment status

Instead of failing the workflow when requesting the deployment status of
a non-existant plan, return a useful message instead.

Change-Id: Ic0333c0726b16d284a7cc54bc68e16ea1c9ebc4d
Partial-Bug: #1792637
(cherry picked from commit 1e13e461cd)

releasenotes/notes/handle-no-deployment-status-a70a4b950171afbe.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - The tripleo.deployment.v1.get_deployment_status workflow will no longer
+    error when requesting the deployment status for a non-existant plan. A
+    message is sent in the output instead of failing the workflow.

workbooks/deployment.yaml

@@ -697,8 +697,8 @@ workflows:
           deployment_status: <% yaml_parse(task().result.last()) %>
         on-complete: send_message
         publish-on-error:
-          status: FAILED
-          message: <% task().result %>
+          message: No deployment status found for plan <% $.plan %>
+          deployment_status: ""
 
       send_message:
         workflow: tripleo.messaging.v1.send