a8n: Empty campaign title caused infinite loop of job being processed

Created by: eseliger

• Sourcegraph version: master

Steps to reproduce:

1. Create a campaign that has an empty title (not possible anymore after #7757, need to remove the db constraint to reproduce, it's still an error swallowed somewhere, so still worth fixing it)
2. See console logs, find gitserver repeatedly creating the commits for the changeset, then frontend logs frontend | ERROR Running campaign job, err: creating changeset: error in GraphQL response: Title can't be blank

Expected behavior:

It's created or the creation fails, and the error is logged in the changeset_jobs table

Actual behavior:

It's not failing, not setting started_at, nor error, causing infinite retries of this job