fix(auth): Run token bulk update statements in atomic transaction

[ChristophWurst]

• Resolves: #

Summary

Ensures that if we want to update all tokens of a user there are no changes between reading the tokens and updating them individually. This change uses the atomic helper function https://docs.nextcloud.com/server/latest/developer_manual/basics/storage/database.html#transactions.

Concurrent requests may otherwise insert, update or delete one of the rows.

This is best reviewed as https://github.com/nextcloud/server/pull/37676/files?w=1 to ignore whitespace changes.

TODO

• Wrap operations in transaction

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)

[szaimen]

CI failure unrelated