Revert "Report exceptions raised during edition workflow"

This reverts commit 4642a9d7f471f6b080c70e54bca6a9e5e4084ac0.

We have had these notifications running for almost two weeks now so have
a handle on the kind of things we need to handle in these workflow
actions.
Merge pull request #1584 from alphagov/stop-workflow-notifications

Revert "Report exceptions raised during edition workflow"