keycloak_user_federation: fix key error when removing mappers in update (#8762)
* remove new mappers without an id from list comprehension
* add changelog fragment
* Update changelogs/fragments/8762-keycloac_user_federation-fix-key-error-when-updating.yml
Co-authored-by: Felix Fontein <felix@fontein.de>
---------
Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit b79ac4f0ac)
Co-authored-by: fgruenbauer <gruenbauer@b1-systems.de>
