refactor: Update Toolbar tests

[neznaika0]

Description
Fix phpstan error:

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  Line   tests/system/Filters/DebugToolbarTest.php                                                    
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  :63    Call to method CodeIgniter\Filters\DebugToolbar::before() on a separate line has no effect.  
         🪪  method.resultUnused                                                                      
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Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide