fix(ui): show file item when search filter matches only test cases

[hi-ogawa]

Description

Closes #4735

The left-most pane uses TasksList.nested = false and TasksTree.nested = false. In this case, hiding TaskItem based on search filter is not necessary since TasksList already decides which file to show based on its own logic.

I haven't added tests (EDIT: e2e is added in 84e5c8d) but manually confirmed the issue from the reproduction is fixed:

Reveal screenshot

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