Remove S3 and accounts displays

[tjsilver]

What does this change?

• Removes the s3 page as the Public Buckets dashboard is now in Grafana.
• Removes the accounts list from Security HQ as the replacement Grafana dashboards can be filtered by account.

What is the value of this?

We are deprecating the Security HQ web app in favour of service catalogue which can provide all the same information and more.

[github-actions[bot]]

Deploy build 2856 of security-hq to CODE

All deployment options

- [Deploy build 2856 of `security-hq` to CODE](https://riffraff.gutools.co.uk/deployment/deployAgain?project=security-hq&build=2856&stage=CODE&updateStrategy=MostlyHarmless&action=deploy) - [Deploy parts of build 2856 to CODE by previewing it first](https://riffraff.gutools.co.uk/preview/yaml?project=security-hq&build=2856&stage=CODE&updateStrategy=MostlyHarmless) - [What's on CODE right now?](https://riffraff.gutools.co.uk/deployment/history?projectName=security-hq&stage=CODE)

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From guardian/actions-riff-raff.