Issue #3341053 by quietone, smustgrave: Move migration tests to the Statistics module

core/.cspell.json

.../Kernel/Migrate/d6/MigrateBlockContentTranslationTest.php

...es/block/tests/src/Kernel/Migrate/d6/MigrateBlockTest.php

.../Kernel/Migrate/d7/MigrateBlockContentTranslationTest.php

...grate/tests/src/Kernel/Plugin/MigrationPluginListTest.php

...s/migrate_drupal/tests/src/Kernel/StateFileExistsTest.php

...rate_drupal_ui/tests/src/Functional/d6/IdConflictTest.php

...ui/tests/src/Functional/d6/MultilingualReviewPageTest.php

.../tests/src/Functional/d6/NoMultilingualReviewPageTest.php

...ate_drupal_ui/tests/src/Functional/d6/NodeClassicTest.php

...igrate_drupal_ui/tests/src/Functional/d6/Upgrade6Test.php

...rate_drupal_ui/tests/src/Functional/d7/IdConflictTest.php

...ui/tests/src/Functional/d7/MultilingualReviewPageTest.php

.../tests/src/Functional/d7/NoMultilingualReviewPageTest.php

...igrate_drupal_ui/tests/src/Functional/d7/Upgrade7Test.php

core/modules/statistics/tests/fixtures/drupal6.php

core/modules/statistics/tests/fixtures/drupal7.php

...tional/migrate_drupal/d6/NoMultilingualReviewPageTest.php

...cs/tests/src/Functional/migrate_drupal/d6/UpgradeTest.php

...ics/tests/src/Functional/migrate_drupal/d6/files/test.txt