Add a dedicated RQ queue for exports.

Refs https://redmine.teklia.com/issues/5584

The export tasks should run on a dedicated RQ queue so we can separate them from other tasks in production to run on servers with large HDDs

arkindex/documents/export/__init__.py

@@ -118,7 +118,7 @@ def send_email(subject, template_name, corpus_export, **context):
         logger.error(f"Failed to send email to {corpus_export.user.email}")
 
 
-@job("high", timeout=settings.RQ_TIMEOUTS["export_corpus"])
+@job("export", timeout=settings.RQ_TIMEOUTS["export_corpus"])
 def export_corpus(corpus_export: CorpusExport) -> None:
     _, db_path = tempfile.mkstemp(suffix=".db")
     try: