[Tests] Replace filesystem mocks in store execute result tests

[gonzaloriestra]

This PR refactors the unit tests for writeOrOutputStoreExecuteResult in the @shopify/store package.

Previously, these tests mocked the @shopify/cli-kit/node/fs module to verify that writeFile was called. This refactor replaces those mocks with real filesystem operations using the inTemporaryDirectory utility and verifies the actual file content using readFile.

Key changes:

• Removed vi.mock('@shopify/cli-kit/node/fs') from packages/store/src/cli/services/store/execute/result.test.ts.
• Wrapped tests that write to a file in inTemporaryDirectory.
• Updated assertions to use readFile to check the written content.
• Ensured renderSuccess is still correctly called with the appropriate file path.

This improvement makes the tests more robust and less coupled to implementation details (like which specific fs function is called).

---

PR created automatically by Jules for task 7901792044942817499 started by @gonzaloriestra

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.