Issue #3139195: Add 'void' return type declarations to test setUp() methods

tests/src/Functional/FillPdfFormDeleteFormTest.php

tests/src/Functional/FillPdfFormDuplicateFormTest.php

tests/src/Functional/FillPdfFormFormTest.php

tests/src/Functional/FillPdfFormImportFormTest.php

tests/src/Functional/FillPdfSettingsFormTest.php

tests/src/Functional/FillPdfTestBase.php

tests/src/Functional/HandlePdfControllerTest.php

tests/src/Functional/LinkManipulatorTest.php

tests/src/Functional/PdfPopulationTest.php

tests/src/Functional/PdfWebformPopulationTest.php

tests/src/Functional/UninstallTest.php

tests/src/Kernel/FillPdfKernelTestBase.php