In Fuel 7.0 we dropped classic provisioning mode,
fully switching to IBP. Remove pre-provision task
of downloading of debian-installer parts and related
script.
Related-Bug: #1549346
Depends-On: I36ff56c1e4a0437b33fc8e31da3df6f311607307
Change-Id: I1001225edd737a29edc263fee48715ba52f53af7