[fix] Load monitoring charts from dashboard domain

Removed OPENWISP_MONITORING_API_BASEURL so that monitoring charts
use relative URLs and load from the dashboard domain.

This fixes SSL certificate issues for users without trusted certs
on the API domain.

Closes #526

Author: Adityashandilya555

images/openwisp_dashboard/module_settings.py

@@ -101,14 +101,12 @@
     else f":{HTTP_PORT}"
 )
 API_BASEURL = f'{HTTP_SCHEME}://{os.environ["API_DOMAIN"]}{HTTP_PORT}'
-DASHBOARD_BASEURL = f'{HTTP_SCHEME}://{os.environ["DASHBOARD_DOMAIN"]}{HTTP_PORT}'
 
 OPENWISP_NETWORK_TOPOLOGY_API_URLCONF = "openwisp_network_topology.urls"
 OPENWISP_MONITORING_API_URLCONF = "openwisp_monitoring.urls"
 OPENWISP_RADIUS_API_URLCONF = "openwisp_radius.urls"
 OPENWISP_NETWORK_TOPOLOGY_API_BASEURL = API_BASEURL
 OPENWISP_NOTIFICATIONS_HOST = API_BASEURL
 OPENWISP_CONTROLLER_API_HOST = API_BASEURL
-OPENWISP_MONITORING_API_BASEURL = DASHBOARD_BASEURL
 OPENWISP_FIRMWARE_API_BASEURL = API_BASEURL
 OPENWISP_RADIUS_API_BASEURL = API_BASEURL