fedora-intune: use Himmelblau instead of the Microsoft Intune app

Go with Entra ID sign-in through Himmelblau for fedora-intune and drop
the Microsoft Intune app (intune-portal, identity broker) variant. With
a single image, the workstation, Edge and Defender manifests move back
from images/shared into images/fedora-intune, and CI builds just that
image again. The Microsoft repo is now limited to mdatp and Edge.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

images/fedora-intune/files/mdatp-firstboot

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+# Finish the Defender (mdatp) install on first boot by running the package's
+# own %post, saved at build time: it creates the machine GUID, state, logs and
+# definitions database under /var and then enables and starts mdatp.service.
+set -euo pipefail
+
+MARKER=/var/lib/mdatp-firstboot.done
+
+[[ -f "${MARKER}" ]] && exit 0
+
+# mdatp.service only starts once the marker exists (10-firstboot.conf), and the
+# %post starts it, so create the marker first and drop it again on failure.
+touch "${MARKER}"
+if ! bash /usr/libexec/mdatp-postinst 1; then
+  rm -f "${MARKER}"
+  exit 1
+fi