handle non-ASCII chars in usage CSV email attachments

[twrichards]

What does this change?

Recent usage emails contained a rare non-breaking space character which broke quotas. We tackle this by dropping non-ASCII characters. Added a test containing CSV which broke things. Also corrected/improved logging of such errors.

## How should a reviewer test this change? The added unit test covers the problematic scenario pretty closely (given the csv content was taken from the email which started breaking stuff). ## How can success be measured? We can ingest usage emails more robustly/flexibly. ## Who should look at this?

Tested? Documented?

• [x] locally by committer
• [ ] locally by Guardian reviewer
• [ ] on the Guardian's TEST environment
• [ ] relevant documentation added or amended (if needed)

[github-actions[bot]]

Deploy build 12585 to TEST

All deployment options

- [Deploy build 12585 to TEST](https://riffraff.gutools.co.uk/deployment/deployAgain?project=media-service%3A%3Agrid%3A%3Aall&build=12585&stage=TEST&updateStrategy=MostlyHarmless&action=deploy) - [Deploy parts of build 12585 to TEST by previewing it first](https://riffraff.gutools.co.uk/preview/yaml?project=media-service%3A%3Agrid%3A%3Aall&build=12585&stage=TEST&updateStrategy=MostlyHarmless)

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From guardian/actions-riff-raff.

[prout-bot]

Seen on auth, usage, image-loader, metadata-editor, thrall, leases, cropper, media-api, kahuna (merged by @twrichards 8 minutes and 35 seconds ago) Please check your changes!

[prout-bot]

Seen on collections (merged by @twrichards 8 minutes and 49 seconds ago) Please check your changes!