Handle PDSCascadingSearchJobs with symbols

In the previous commit this job was converted to use string arguments.
This adds a fallback to ensure that if any existing jobs with symbols
are executed correctly.

Jira-Issue: MAV-7288

Author: thomasleese

app/jobs/pds_cascading_search_job.rb

@@ -11,6 +11,10 @@ def perform(searchable, step_name: nil, search_results: nil, queue: nil)
     search_results ||= []
     queue ||= "pds"
 
+    # FIXME: Remove these once we're not queuing jobs using symbols.
+    step_name = step_name.to_s
+    queue = queue.to_s
+
     SemanticLogger.tagged(
       searchable: "#{searchable.class.name}##{searchable.id}",
       step: step_name