Add minimal e2e test for ecs_fargate integration

[alopezz]

What does this PR do?

Adds an e2e test to ecs_fargate that asserts that a critical check is emitted, as there's no service running.

Motivation

AI-2508

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] PR title must be written as a CHANGELOG entry (see why)
• [ ] Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• [ ] PR must have changelog/ and integration/ labels attached

[codecov[bot]]

Codecov Report

Merging #12954 (a87bbc5) into master (cd4cd84) will decrease coverage by 0.00%. The diff coverage is 71.42%.

Flag	Coverage Δ
ecs_fargate	80.05% <71.42%> (-0.18%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.