dvc: remove dvc.data, fix imports

tests/func/test_external_repo.py

@@ -3,11 +3,11 @@ from unittest.mock import ANY
 
 from scmrepo.git import Git
 
-from dvc.data.stage import stage
-from dvc.data.transfer import transfer
 from dvc.external_repo import CLONES, external_repo
 from dvc.utils import relpath
 from dvc.utils.fs import makedirs, remove
+from dvc_data.stage import stage
+from dvc_data.transfer import transfer
 from tests.unit.fs.test_dvc import make_subrepo
 from tests.utils import clean_staging