ostree: create file `/run/ostree-booted` in initramfs

This file is required by recent libostree versions for several
operations like `ostree admin upgrade` to be sure we are booted in
ostree-based system. So just create this file in initramfs script
responsible for mounting ostree structure.

Check APERTIS-5762 for additional details.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>

overlays/ostree/usr/share/initramfs-tools/scripts/init-bottom/ostree

@@ -25,3 +25,8 @@ cd -
 ## move the deployment to the sysroot
 mount --move $sysroot$ostree $sysroot
 ## after these the init system should start the switch root process
+
+## Mark the system is ostree-booted
+#  TODO: remove this "touch" after resolving the task APERTIS-5762
+#  Do not fail here if /run is not available or not mounted
+touch /run/ostree-booted || true