fix(settings): update all button only updates a single app

[tmlmt]

• Resolves: #51318

Summary

Previously, the chain of functions involved in the "update all apps" routine were not properly setup up with regards to asynchronism:

• The promises generated by updateAll() were not awaited or managed properly
• The update function fed to p-limit's limit() utility was returning void and not a promise, as it expects (see docs)

This was causing the mechanism driving the updates to potentially end prematurely.

This PR fixes this by:

• Properly using async/await and Promises.all in updateAll() to ensure all promises generated by p-limit are awaited and executed completely before the function finishes.
• Making update() return the promises it involves

This would prevent the function from exiting prematurely and ensure all updates are processed automatically.

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)
• [ ] Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• [ ] Milestone added for target branch/version (ex: 32.x for stable32)

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[DaphneMuller]

@susnux @CarlSchwan any chance this can be merged?