Test: Refactor test fixtures to use HttpApiAuth naming consistently (#8180)

### What problem does this PR solve?

- Rename `api_key` fixture to `HttpApiAuth` across all test files
- Update all dependent fixtures and test cases to use new naming
- Maintain same functionality while improving naming clarity

The rename better reflects the fixture's purpose as an HTTP API
authentication helper rather than just an API key.

### Type of change

- [x] Refactoring

test/testcases/test_http_api/test_dataset_mangement/conftest.py

@@ -20,20 +20,20 @@ from common import batch_create_datasets, delete_datasets
 
 
 @pytest.fixture(scope="class")
-def add_datasets(api_key, request):
+def add_datasets(HttpApiAuth, request):
     def cleanup():
-        delete_datasets(api_key, {"ids": None})
+        delete_datasets(HttpApiAuth, {"ids": None})
 
     request.addfinalizer(cleanup)
 
-    return batch_create_datasets(api_key, 5)
+    return batch_create_datasets(HttpApiAuth, 5)
 
 
 @pytest.fixture(scope="function")
-def add_datasets_func(api_key, request):
+def add_datasets_func(HttpApiAuth, request):
     def cleanup():
-        delete_datasets(api_key, {"ids": None})
+        delete_datasets(HttpApiAuth, {"ids": None})
 
     request.addfinalizer(cleanup)
 
-    return batch_create_datasets(api_key, 3)
+    return batch_create_datasets(HttpApiAuth, 3)