add ImageLoaderMetrics - track successful, fail and abandoned ingests

[dblatcher]

What does this change?

add ImageLoaderMetrics - track successful, fail and abandoned ingest from queue.

## How should a reviewer test this change? Deploy to TEST, ingest some files - check that the metrics for the TEST cloud metrics for ImageLoader show the activity. ## How can success be measured? The new metrics will be viewable on the AWS cloudwatch console and useable for setting alarms. ## Who should look at this?

Tested? Documented?

• [ ] 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 12239 to TEST

All deployment options

- [Deploy build 12239 to TEST](https://riffraff.gutools.co.uk/deployment/deployAgain?project=media-service%3A%3Agrid%3A%3Aall&build=12239&stage=TEST&updateStrategy=MostlyHarmless&action=deploy) - [Deploy parts of build 12239 to TEST by previewing it first](https://riffraff.gutools.co.uk/preview/yaml?project=media-service%3A%3Agrid%3A%3Aall&build=12239&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 @dblatcher 8 minutes and 44 seconds ago) Please check your changes!

[prout-bot]

Seen on collections (merged by @dblatcher 8 minutes and 54 seconds ago) Please check your changes!