fix(artifacts): Fix successful filter for find artifacts (#2780)

When filtering to only include successful executions, the
front-end sets the flag 'successful' in the stage config.
Orca is incorrectly looking for a value 'succeeded', and
thus ignores the value that was set on the front-end.

While 'succeeded' is slightly better named as it matches the
execution status, changing this on the backend means that
existing pipelines will work automatically.  (Whereas changing
it on the front-end would require either a pipeline migrator
or for anyone affected to re-configure the stage.)

To avoid breaking anyone who manually edited their stage config to
set 'succeeded' because that's what the back-end was looking for,
continue to accept that in the stage config.

orca-clouddriver/src/main/groovy/com/netflix/spinnaker/orca/clouddriver/tasks/artifacts/FindArtifactFromExecutionTask.java

@@ -73,13 +73,18 @@ public TaskResult execute(@Nonnull Stage stage) {
 
   @Data
   private static class ExecutionOptions {
+    // Accept either 'succeeded' or 'successful' in the stage config. The front-end sets 'successful', but due to a bug
+    // this class was only looking for 'succeeded'. Fix this by accepting 'successful' but to avoid breaking anyone who
+    // discovered this bug and manually edited their stage to set 'succeeded', continue to accept 'succeeded'.
     boolean succeeded;
+    boolean successful;
+
     boolean terminal;
     boolean running;
 
     ExecutionCriteria toCriteria() {
       List<String> statuses = new ArrayList<>();
-      if (succeeded) {
+      if (succeeded || successful) {
         statuses.add("SUCCEEDED");
       }