fix(caldav, carddav): also allow unsharing of circle shares

[miaulalala]

• Resolves: #

Summary

Unsharing a group share should also be possible for Circle group shares

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Backports requested where applicable (ex: critical bugfixes)

[miaulalala]

/backport to stable30

[miaulalala]

/backport to stable29

[miaulalala]

/backport to stable28

[kesselb]

LGTM 👍

Commit message needs an update

[st3iny]

Looks good but didn't test.

[backportbot]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b backport/47737/stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 17ef20c5

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/47737/stable28

Error: No changes found in backport branch

---

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

[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/47737/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 17ef20c5

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/47737/stable29

Error: Failed to push branch backport/47737/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.