Remove configure AWS credentials jobs from workflow templates

https://github.com/guardian/.github/blob/35792e30e4b827167a11d438eadba78ada2ebf72/workflow-templates/ci-sbt.yml#L27


This approach is no longer recommended as v4 of [actions-riff-raff](https://github.com/guardian/actions-riff-raff) handles this for us. We should remove this step from all relevant workflows in the repo