manifests: enable OSTree autopruning for ppc64le

The ppc64le arch has been blocked [1] from being fully released because
of size limitations in /boot not being able to hold 3 copies of
kernel+initramfs becaue the kernel on ppc64le isn't compressed [2].
Now that OSTree Autopruning [3] has landed let's enable it on ppc64le
to unblock ourselves.

[1] coreos/fedora-coreos-tracker#987 (comment)
[2] coreos/fedora-coreos-tracker#1247 (comment)
[3] coreos/fedora-coreos-tracker#1495

manifests/fedora-coreos.yaml

@@ -23,6 +23,12 @@ conditional-include:
   - if: basearch != "s390x"
     # And remove some cruft from grub2
     include: grub2-removals.yaml
+  - if: basearch == "ppc64le"
+    # Need OSTree autopruning on ppc64le (because kernels aren't compressed)
+    # until we increase the size of /boot.
+    # https://github.com/coreos/fedora-coreos-tracker/issues/1247#issuecomment-1355314761
+    # https://github.com/coreos/fedora-coreos-tracker/issues/1495#issuecomment-1561765705
+    include: ostree-autoprune.yaml
 
 ostree-layers:
   - overlay/15fcos

manifests/ostree-autoprune.yaml

@@ -0,0 +1,10 @@
+
+postprocess:
+  # Enable OSTree autopruning to help with /boot size constraints
+  # https://github.com/coreos/fedora-coreos-tracker/issues/1495
+  - |
+    #!/usr/bin/env bash
+    mkdir -p /usr/lib/systemd/system/rpm-ostreed.service.d
+    overrides_file=/usr/lib/systemd/system/rpm-ostreed.service.d/ostree-autoprune.conf
+    echo "# https://github.com/coreos/fedora-coreos-tracker/issues/1495" > $overrides_file
+    echo "OSTREE_ENABLE_AUTO_EARLY_PRUNE=1" >> $overrides_file