[bug] USE_OPENWISP_TOPOLOGY not taken into account in load_init_data script

[keviiin38]

Describe the bug
When using the Docker Compose setup with the USE_OPENWISP_TOPOLOGY set to False the dashboard service won't start due to an error.

docker-openwisp-dashboard-1  | Running migrations:
docker-openwisp-dashboard-1  |   No migrations to apply.
docker-openwisp-dashboard-1  | Traceback (most recent call last):
docker-openwisp-dashboard-1  |   File "/opt/openwisp/load_init_data.py", line 258, in <module>
docker-openwisp-dashboard-1  |     Topology = load_model('topology', 'Topology')
docker-openwisp-dashboard-1  |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
docker-openwisp-dashboard-1  |   File "/usr/local/lib/python3.12/site-packages/swapper/__init__.py", line 79, in load_model
docker-openwisp-dashboard-1  |     raise ImproperlyConfigured(
docker-openwisp-dashboard-1  | django.core.exceptions.ImproperlyConfigured: Could not find topology.Topology!
docker-openwisp-dashboard-1 exited with code 0

Steps To Reproduce
Steps to reproduce the behavior:

1. Clone the https://github.com/openwisp/docker-openwisp repository
2. Edit the .env file and replace USE_OPENWISP_TOPOLOGY=True with USE_OPENWISP_TOPOLOGY=False
3. Start the Docker Compose stack using docker compose up -d
4. See the error in the logs of the dashboard service using docker compose logs -f dashboard

Expected behavior
The dashboard service should not fail, and the script load_init_data.py should not exit when the variable USE_OPENWISP_TOPOLOGY is set to False

The script should check the variable value differently here : https://github.com/openwisp/docker-openwisp/blob/master/images/openwisp_dashboard/load_init_data.py#L258

-   if os.environ.get('USE_OPENWISP_TOPOLOGY', False):
+   if os.environ.get('USE_OPENWISP_TOPOLOGY', False) == "True":
        Topology = load_model('topology', 'Topology')
        create_default_topology(default_vpn)

Screenshots
n/a

System Informatioon:

• OS: Ubuntu 22.04 LTS
• Docker version: Docker version 24.0.7, build 311b9ff