🛂(backend) stop throttling collaboration servers

We observe some throttling pick here and there.
We observed that when the collaboration has a
problem, it is retrying to connect, leading to more
requests to the django backend. At one point, the
throttling is reached and the user would not
be able to use the application anymore.
Now when the request comes from a collaboration
server, we do not throttle it anymore.

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to
 
 ### Changed
 
+- 🛂(backend) stop throttling collaboration servers #1730
 - 🚸(backend) use unaccented full name for user search #1637
 - 🌐(backend) internationalize demo #1644