Prevent formatting the kptfile during upgrades

[ciaranjohnston]

Describe your problem

As discussed during the Nephio meetup in September 2025, we want to prevent formatting the kptfile during upgrades:

• Keep the original comments and formatting of kptfile
• In the new SDK there is a go package called kptfile. Using this go package will preserve most of the formatting.
• We need an issue to change the kpt to use the kptfile go package -> @lapentad