Remove deprecated external storage tests

Remove test files that depend on the deprecated datajoint.external module
which was removed in 2.0:
- tests/test_external.py
- tests/test_external_class.py
- tests/test_attach.py
- tests/test_filepath.py
- tests/test_s3.py
- tests/schema_external.py

Also remove related fixtures from conftest.py.

Co-authored-by: dimitri-yatsenko <dimitri@datajoint.com>

Author: claude

tests/conftest.py

@@ -15,11 +15,8 @@
 from packaging import version
 
 import datajoint as dj
-from datajoint.errors import (
-    FILEPATH_FEATURE_SWITCH,
-)
 
-from . import schema, schema_advanced, schema_external, schema_object, schema_simple
+from . import schema, schema_advanced, schema_object, schema_simple
 from . import schema_uuid as schema_uuid_module
 from . import schema_type_aliases as schema_type_aliases_module
 
@@ -327,13 +324,6 @@ def enable_adapted_types():
     yield
 
 
-@pytest.fixture
-def enable_filepath_feature(monkeypatch):
-    monkeypatch.setenv(FILEPATH_FEATURE_SWITCH, "TRUE")
-    yield
-    monkeypatch.delenv(FILEPATH_FEATURE_SWITCH, raising=True)
-
-
 @pytest.fixture(scope="session")
 def db_creds_test(mysql_container) -> Dict:
     _, host, port = mysql_container
@@ -710,25 +700,6 @@ def schema_adv(connection_test, prefix):
     schema.drop()
 
 
-@pytest.fixture
-def schema_ext(connection_test, enable_filepath_feature, mock_stores, mock_cache, prefix):
-    schema = dj.Schema(
-        prefix + "_extern",
-        context=schema_external.LOCALS_EXTERNAL,
-        connection=connection_test,
-    )
-    schema(schema_external.Simple)
-    schema(schema_external.SimpleRemote)
-    schema(schema_external.Seed)
-    schema(schema_external.Dimension)
-    schema(schema_external.Image)
-    schema(schema_external.Attach)
-    schema(schema_external.Filepath)
-    schema(schema_external.FilepathS3)
-    yield schema
-    schema.drop()
-
-
 @pytest.fixture(scope="module")
 def schema_uuid(connection_test, prefix):
     schema = dj.Schema(