docs: update service worker section in Web FAQ

[harshyadavDeveloper]

Description

Updates the Web FAQ to reflect the current state of service worker support.

Removes outdated references to the --pwa-strategy flag and clarifies that Flutter no longer generates or manages a service worker by default.

Issues fixed by this PR

Closes #13319

PRs or commits this PR depends on

None

Presubmit checklist

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• This PR follows the [Google Developer Documentation Style Guidelines](https://developers.google.com/style)—for example, it doesn't use i.e. or e.g., and it avoids I and we (first-person pronouns).
• This PR uses [semantic line breaks](https://github.com/dart-lang/site-shared/blob/main/doc/writing-for-dart-and-flutter-websites.md#semantic-line-breaks)
  of 80 characters or fewer.

[harshyadavDeveloper]

Hi! I’ve updated the service worker section to remove outdated references to the --pwa-strategy flag and clarified the current behavior. Please let me know if any adjustments are needed.

[gemini-code-assist]

Code Review

This pull request updates the Flutter web FAQ to clarify that service workers are no longer generated or managed by default, recommending manual configuration or third-party tools like Workbox for offline support. A review comment suggests improving the readability of a documentation link by using descriptive text instead of a technical identifier.

[flutter-website-bot]

Visit the preview URL for this PR (updated for commit 9647125):

https://flutter-docs-prod--pr13335-fix-remove-pwa-strategy-faq-zcs5sbmn.web.app

[harshyadavDeveloper]

Thanks for pointing this out! I’ve removed the remaining ios-ffi reference usages to avoid broken links.

[parlough]

/gcbrun

[harshyadavDeveloper]

Hello, this PR currently has merge conflicts blocking the merge. Could you please take a look and resolve them at your convenience?