Issue #3477613 by quietone: Add doc block for $modules in tests

core/modules/block/tests/src/Kernel/BlockInterfaceTest.php

...s/src/Kernel/Migrate/MigrateBlockContentBodyFieldTest.php

.../tests/src/Kernel/Migrate/MigrateBlockContentTypeTest.php

...nt/tests/src/Kernel/Migrate/d7/MigrateCustomBlockTest.php

...odules/comment/tests/src/Functional/CommentFieldsTest.php

...es/comment/tests/src/Functional/CommentLinksAlterTest.php

...dules/comment/tests/src/Functional/CommentNonNodeTest.php

...ests/src/Functional/ConfigTranslationDateFormatUiTest.php

...el/Migrate/d6/MigrateSystemMaintenanceTranslationTest.php

...rc/Kernel/Migrate/d6/MigrateSystemSiteTranslationTest.php

...c/Kernel/Migrate/d6/MigrateUserConfigsTranslationTest.php

...el/Migrate/d7/MigrateSystemMaintenanceTranslationTest.php

...s/src/Functional/ContentTranslationEntityBundleUITest.php

...ation/tests/src/Kernel/ContentTranslationSyncUnitTest.php

...ctional/EntityReference/EntityReferenceAutoCreateTest.php

...ctional/EntityReference/EntityReferenceFileUploadTest.php

...c/Kernel/Migrate/d7/MigrateFieldFormatterSettingsTest.php

...ield/tests/src/Kernel/Migrate/d7/MigrateViewModesTest.php

core/modules/filter/tests/src/Kernel/FilterAPITest.php

...dules/filter/tests/src/Kernel/FilterDefaultConfigTest.php