minimal/systemd-presets: preset dnf-makecache.timer to disabled

This one doesn't make much sense to have enabled by default on systems
with image based updates because we shouldn't need a local cache of
yum repo metadata (i.e. we should just be interacting with a registry).

minimal/systemd-presets.yaml

@@ -1,5 +1,14 @@
 # Postprocessing relating to systemd presets on the system.
 postprocess:
+  - |
+    #!/bin/bash
+    set -xeuo pipefail
+    # Override some of the default presets.
+    cat <<EOF > usr/lib/systemd/system-preset/85-bootc.preset
+    # Disable dnf-makecache.timer on bootc/image mode systems
+    # https://github.com/coreos/fedora-coreos-tracker/issues/1896#issuecomment-2848251507
+    disable dnf-makecache.timer
+    EOF
   # Undo RPM scripts enabling units; we want the presets to be canonical
   # https://github.com/projectatomic/rpm-ostree/issues/1803
   - |