Switch Azure CI to Fedora 36 pre-release

Use fedora-toolbox:36 image as it is prepared to work with systemd and
sudo

Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>

ipatests/azure/Dockerfiles/Dockerfile.build.fedora

@@ -1,4 +1,4 @@
-FROM fedora:34
+FROM registry.fedoraproject.org/fedora-toolbox:36
 MAINTAINER [FreeIPA Developers freeipa-devel@lists.fedorahosted.org]
 ENV container=docker LANG=en_US.utf8 LANGUAGE=en_US.utf8 LC_ALL=en_US.utf8
 

ipatests/azure/templates/variables-fedora.yml

@@ -1,7 +1,7 @@
 variables:
   IPA_PLATFORM: fedora
   # the Docker public image to build IPA packages (rpms)
-  DOCKER_BUILD_IMAGE: 'fedora:34'
+  DOCKER_BUILD_IMAGE: 'registry.fedoraproject.org/fedora-toolbox:36'
 
   # the Dockerfile to build Docker image for running IPA tests
   DOCKER_DOCKERFILE: ${{ format('Dockerfile.build.{0}', variables.IPA_PLATFORM) }}