Details: Since this is the first Debian to Debian upgrade,
we need to refactor some existing code that is used for
centOS upgrade.
This commit is
1. clean up CentOS related code
2. copy to-load pxeboot-update.sh to /etc/ during the import
instead of /usr/sbin/
3. install to-load pxeboot-update.sh in /etc/ instead of
/usr/sbin/ during iso installation
4. update kickstart Upgrade Support accordingly to set up
from-load feed
Test Plan:
PASS: built the iso for upgrade
PASS: upgraded from 22.12 to 23.09 in DX
PASS: downgrade from 23.09 to 22.12 in DX
Depends-on: https://review.opendev.org/c/starlingx/tools/+/881882
Task: 47805
Story: 2010651
Signed-off-by: Junfeng (Shawn) Li <junfeng.li@windriver.com>
Change-Id: Ia67f5f3e66f5b33c3d7fb8d93a15547d59eaa71e
d9d7111cd8