The tenant task list says "Unassigned" in English on every site, from a view setting that cannot be translated

Problem/Motivation

On the manager's tenant task list, a task nobody holds yet shows Unassigned in the Assignee column, in English, whatever the site's language. The word is the column's "No results text" in the shipped views.view.orchestra_inbox, and core types that setting as a plain string in its views schema, not as translatable text, so no catalog can reach it.

It also says less than the rest of the project does about such a task. The Held by column on the personal task lists, and the inbox, name who an unassigned task is offered to: Offered to: Reviewers, or (anyone). That is the question a manager is asking of the list.

Proposed resolution

• The Assignee column names the pool itself when a task has no assignee, with the wording WorkItemManager::getHolderLabel() already gives the Held by column: translated, and the same everywhere. An assigned task still shows the assignee's name, linked as before.
• The pooled-row work the Held by column does (naming the page's pools in one pass, and putting the named roles' and accounts' cache tags on the render) is shared between the two columns rather than written twice.
• The shipped view drops its untranslatable empty text.

Remaining tasks

None beyond the change and its test.

AI-Generated: Yes (Claude Code found this on a French site after deploying the previous fixes, drafted this issue summary, and wrote the change and its tests on the merge request.)