fix(appstore): Hide last modified information for shipped apps

[SystemKeeper]

• Resolves: Shipped apps previously released via the app store show "Last updated" date based on legacy app store entry not installed app #45717

Summary

Don't show the last modified information for apps that are shipped.

Before:

After:

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[provokateurin]

/backport to stable30

[provokateurin]

/backport to stable29

[provokateurin]

/backport to stable28

[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/48743/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 74d179ed

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/48743/stable28

Error: No changes found in backport branch

---

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

[SystemKeeper]

In 28 we don't show the last modified information it seems -> skipping the backport.