fix: use order item QTY to create subscription

[Francois-Gomis]

Reason for change

Buy product with insurance with qty 2

Linear task

Code changes

How to test

As a reviewer, you are encouraged to test the PR locally.

Checklist for authors and reviewers

• [ ] The title of the PR uses business wording, not technical jargon, for the changelog readers to understand it
• [ ] The PR implements the changes asked in the referenced task / issue
• [ ] The automated tests are compliant with the testing strategy
• [ ] The tests are relevant, and cover the corner/error cases, not only the happy path
• [ ] You understand the impact of this PR on existing code/features
• [ ] The changes include adequate logging and Datadog traces
• [ ] Documentation is updated (API, developer documentation, ADR, Notion...)

Non applicable

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
66.3% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud