🛂(backend) do not duplicate user when disabled

When a user is disabled and tries to login, we
don't want the user to be duplicated,
the user should not be able to login.

Fixes #324

Work initially contributed by @qbey on:
https://github.com/numerique-gouv/people/pull/456

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to
 
 ## Fixed
 
+- 🛂(backend) do not duplicate user when disabled
 - 🐛(frontend) invalidate queries after removing user #336
 - 🐛(backend) Fix dysfunctional permissions on document create #329
 - 🐛(backend) fix nginx docker container #340