Increase export job check timeout

This PR greatly increases the number of times manifester will check the
status of a manifest export job in RHSM before timing out. This is
intended to address scenarios in which there is a significant gap
between an export job being scheduled in RHSM and the job starting
execution.

manifester/manifester.py

@@ -339,7 +339,7 @@ def trigger_manifest_export(self):
         Starts the export job, monitors the status of the job, and downloads the manifest on
         successful completion of the job.
         """
-        MAX_REQUESTS = 50
+        MAX_REQUESTS = 500
         SUCCESS_CODE = 200
         data = {
             "headers": {"Authorization": f"Bearer {self.access_token}"},