Issue #2674408 by alexpott: Fix "Drupal.Classes.UnusedUseStatement" standard in core

...el/Migrate/d6/MigrateCommentVariableEntityDisplayTest.php

...igrate/d6/MigrateCommentVariableEntityFormDisplayTest.php

core/modules/file/tests/src/Kernel/ValidateTest.php

core/modules/hal/tests/src/Kernel/DenormalizeTest.php

core/modules/hal/tests/src/Kernel/EntityNormalizeTest.php

core/modules/hal/tests/src/Kernel/FileNormalizeTest.php

core/modules/hal/tests/src/Kernel/NormalizeTest.php

.../modules/migrate/tests/src/Kernel/MigrateRollbackTest.php

core/modules/migrate/tests/src/Kernel/SqlBaseTest.php

...rate_drupal/tests/src/Kernel/d6/EntityContentBaseTest.php

...ser/tests/src/Kernel/Views/HandlerFieldPermissionTest.php

...es/user/tests/src/Kernel/Views/HandlerFilterRolesTest.php

...sts/src/Kernel/Handler/EntityTestViewsFieldAccessTest.php

core/modules/views/tests/src/Kernel/Plugin/JoinTest.php

...iews/tests/src/Kernel/Plugin/RelationshipJoinTestBase.php

...odules/views/tests/src/Kernel/Plugin/RelationshipTest.php

...odules/views/tests/src/Kernel/Plugin/StyleMappingTest.php

core/modules/views/tests/src/Kernel/QueryGroupByTest.php

core/modules/views/tests/src/Kernel/ViewExecutableTest.php

core/modules/views/tests/src/Kernel/ViewsHooksTest.php