fix: correct userGroups intersection check for federation access

[sanskar-soni-9]

Fixed isFederatedEnabledForUser, which was returning true when the intersection of allowedGroups and userGroups was empty. Now it correctly returns true when the intersection is not empty.

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not possible
• 📘 API documentation in docs/ has been updated or is not required
• 🔖 Capability is added or not needed

[sanskar-soni-9]

also it returns true when there are no allowedGroups is that intended?

[nickvergessen]

also it returns true when there are no allowedGroups is that intended?

Yeah, that is basically the default

[nickvergessen]

/backport to stable30

[nickvergessen]

/backport to stable29

[backportbot]

The backport to stable29 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable29
git pull origin stable29

# Create the new backport branch
git checkout -b backport/13030/stable29

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 6d4c528c

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/13030/stable29

Error: Failed to push branch backport/13030/stable29: fatal: could not read Username for 'https://github.com': No such device or address

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[nickvergessen]

Backport to 29 in #13067 (comment)

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