Description

The purpose of this PR is to:

• Remove a redundant eventbus DLQ now that the eventbus lambda is behind an SQS queue module which creates its own DLQ.
• Update the eventbus lambda to return errors as batch item failures instead of putting items manually on a DLQ.
• Update the Queue and DLQ names created for the eventbus lambda in order to remove a duplicate csi component. For example, it used to show as nhs-main-dl-nhs-main-dl-eventpub-queue in the Digital Letters bounded context, with this update it will now show as nhs-main-dl-eventpub-queue.

This is a breaking change as it will delete existing queues and create new ones. A plan needs to be put in place for bounded context that want to use this version.

More testing done as part of https://github.com/NHSDigital/nhs-notify-digital-letters/pull/416

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.