This patch is adds a new grub2 element that installs the
grub2 bootloader on the image so it can work with Ironic's
local boot support.
This patch also modifies the iso element which was installing
same grub2. It removes the grub2 installation from iso element
and makes it dependent on grub2 element.
Co-Authored-By: Ramakrishnan G <rameshg87@gmail.com>
Change-Id: I37bcf2c525708d1e2e0f95cf5874a279f76861f7
