🗑️(backend) remove useless analytics settings

Remove useless analytics key settings as we removed tracking
data from the backend code.

src/backend/meet/settings.py

@@ -401,9 +401,6 @@ class Base(Configuration):
     ALLOW_UNREGISTERED_ROOMS = values.BooleanValue(
         True, environ_name="ALLOW_UNREGISTERED_ROOMS", environ_prefix=None
     )
-    ANALYTICS_KEY = values.Value(
-        None, environ_name="ANALYTICS_KEY", environ_prefix=None
-    )
 
     # pylint: disable=invalid-name
     @property