fedora-intune: install Defender from Microsoft's Fedora 44 repo

The RHEL 10 repo was there for the Intune app, which only ships for RHEL;
that app is gone and the repo now only provides mdatp. Use Microsoft's
Fedora 44 repo instead: Fedora is a supported Defender distribution
(servers and the Linux desktop preview), and it carries a newer build
(101.26091.0003 vs 101.26081.0010 in the RHEL 10 repo). Same signing key
and signed metadata.

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

images/fedora-intune/build.conf

@@ -4,7 +4,7 @@ BUILD_MODE=upstream
 
 UPSTREAM_REPO="https://gitlab.com/fedora/ostree/ci-test.git"
 
-# Stable only; Defender comes from Microsoft's RHEL 10 repo, not rawhide.
+# Stable only; Microsoft's Defender repo (fedora/44) has no rawhide build.
 declare -A UPSTREAM_REFS=(
   [44]=f44
 )