This commit is to remove legacy upgrade code in update repo.
After removal, the USM is used for platform upgrade.
Test Plan:
PASS: build the iso
PASS: deploy iso in SX
PASS: deploy iso in DX
Task: 50259
Story: 2010676
Change-Id: If2020a6f529ab478f4bd048fdf7c14e9bf462ed6
Signed-off-by: junfeng-li <junfeng.li@windriver.com>