OC-925: Configure ECS task to run on a schedule

[finlay-jisc]

The purpose of this PR was to set up the ARI import ECS task to run automatically at a scheduled time. This should finish off the ECS solution, ready for its ongoing usage. On Tuesday mornings, an incremental update runs on int, and at the same time, a dry run incremental update runs on prod. The results will be checked on int and the output report emails will be reviewed before triggering a real incremental update on prod via the API endpoint.

The API code around the trigger endpoint has been tidied up and the naming has been updated to refer to ARI imports specifically rather than generic ECS triggering.

The code hasn't been deployed to prod yet but I have double checked that the dry run override works on the int trigger.

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Acceptance Criteria:

• A schedule rule exists that triggers the ARI import function at 5am on int and prod
  • On prod, this execution is a dry run
• ARI import runs can be triggered (dry runs and actual runs) via the API endpoint

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Checklist:

• Local manual testing conducted
• Automated tests added
• Documentation updated

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Tests:

API

E2E

[adwearing-jisc]

Few potential improvements. No deal breakers, I think it's fine without, just possible to improve readability and terraform usage.