Revert igwn alert task fix once IGWN Alert updates to hop-client >= 0.6.0

The fix in !887 (merged) will probably need to be reverted once IGWN-Alert updates to hop-client >= 0.6.0. I assume that the IGWN-Alert listener will parse the JSONBlob that hop-client >= 0.6.0 sends for us and then we'll just receive the alert dictionary like before, though it's possible they'll just pass the full kafka message to us and we'll need to keep the changes from !887 (merged). If that happens, we'll need to remove the FIXMEs introduced by that MR.