This commit is to move the pxe files import functionality from
major-release-upload script to deploy start. This change is
needed to work with DC subcloud upgrade as the
major-release-upload script is not run during the subcloud
upgrade prestaging.
Test Plan:
PASS: build and deploy iso to DX
PASS: upgrade DX from stx10 to stx11
PASS: rollback DX from stx11 to stx10
PASS: subcloud upgrade from stx10 to stx11
PASS: subcloud rollback from stx11 to stx10
Task: 52863
Story: 2011357
Change-Id: I3e4176d455c15ceda5d0249103947b7939724b72
Signed-off-by: junfeng-li <junfeng.li@windriver.com>