tests: update env.py and conftest so tests use unique databases (#3654)

* Refactor Alembic environment script to simplify database connection logic and remove unused imports

* Refactor test client fixture to use TemporaryDirectory and UUID for database path

* Add `reload_engine` method to reinitialize the database engine

* Add cleanup steps to test fixtures to ensure proper resource management

- Added cleanup steps to various pytest fixtures to ensure temporary directories, database entries, and other resources are properly cleaned up after tests.
- Modified fixtures to use `yield` for better resource management.
- Ensured database connections are closed and tables are dropped after tests.
- Improved temporary directory handling with context managers.

* Add unit test to verify return type of list_flows method in custom component

* Refactor tests in `test_custom_component.py` to remove unused imports and fixtures, and update existing fixtures for consistency.

* Add debug checks for user existence in `test_user_waiting_for_approval` test

* Fix import order and add flow_id validation in transaction handling

- Corrected the import order in `utils.py`.
- Added validation for `flow_id` in the transaction handling logic to ensure it is set correctly.

* Add function to delete transactions by flow ID in CRUD module

* Add cleanup for transactions and vertex builds in test teardown

- Introduced `_delete_transactions_and_vertex_builds` function to remove transactions and vertex builds associated with a user.
- Updated `user` fixture to call the new cleanup function before deleting the user.

* Refactor flow_id assignment logic in `utils.py` to improve readability and correctness

* [autofix.ci] apply automated fixes

* Refactor test to use pytest's tmp_path fixture for temporary directory creation

* Convert `test_user_waiting_for_approval` to an async test function

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/backend/tests/unit/test_cli.py

@@ -1,6 +1,3 @@
-from pathlib import Path
-from tempfile import tempdir
-
 import pytest
 
 from langflow.__main__ import app
@@ -15,13 +12,9 @@ def default_settings():
     ]
 
 
-def test_components_path(runner, client, default_settings):
-    # Create a foldr in the tmp directory
-
-    temp_dir = Path(tempdir)
+def test_components_path(runner, client, default_settings, tmp_path):
     # create a "components" folder
-    temp_dir = temp_dir / "components"
-    temp_dir.mkdir(exist_ok=True)
+    temp_dir = tmp_path / "components"
 
     result = runner.invoke(
         app,