Particularly the line with `within "tr", text: "Finished budget" do` is
now easier to read.
This way we avoid a potential pitfall. Imagine that the factory which
creates a finished budget generated a budget with the name "COMPLETED
Budget 1". Then the test:
```
within "#budget_#{finished_budget.id}" do
expect(page).to have_content("COMPLETED")
end
```
Would pass even if we didn't add the text "COMPLETED" anywhere else,
because it would be included in the name of the budget.
0eedc7b6ab