Revert "use debconf module instead of shell command"

openbox autostart calls the autostart script with sh as shell and
using ansible's debconf module does not change dash to bash
successfully, so for the moment we need to use the shell command instead.

This reverts commit 4170935a5a.

roles/grub-config/handlers/main.yml

@@ -1,10 +1,5 @@
 ---
 
-- name: Update Initramfs
-  command: "update-initramfs -u"
-  failed_when: ('error' in initramfs_register_update.stderr)
-  register: initramfs_register_update
-
 - name: Update GRUB
   command: update-grub
   failed_when: ('error' in grub_register_update.stderr)