fix: Allow teardown to use FLAGSMITH_API_URL

[kyle-ssg]

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• I have added information to docs/ if required so people know about the feature!
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Changes

Uses FLAGSMITH_API_URL for the e2e teardown if it is set.

How did you test this code?

Confirmed FLAGSMITH_API_URL=x npm run test uses the correct teardown.

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Name	Status	Preview	Comments	Updated (UTC)
flagsmith-frontend-preview	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 20, 2024 10:36am
flagsmith-frontend-staging	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 20, 2024 10:36am

1 Skipped Deployment

Name	Status	Preview	Comments	Updated (UTC)
docs	⬜️ Ignored (Inspect)			Nov 20, 2024 10:36am

[github-actions]

Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-api-test:pr-4849	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-e2e:pr-4849	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api:pr-4849	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith:pr-4849	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-4849	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-frontend:pr-4849	Finished ✅	Results ✅

[github-actions]

Uffizzi Preview deployment-58401 was deleted.