[Merge] ~juliank/ubuntu-release-upgrader:ubuntu/noble into ubuntu-release-upgrader:ubuntu/noble

[Julian Andres Klode]

The u-r-u change works in that it restores the previous behavior, however that is buggy:

- It now removes the linux headers that it is supposed to protect. Because it is called once each for 
  linux-headers-6.5.0-44 and linux-headers-6.5.0-44-generic; in the latter case, we correctly skip it,
  but when we remove linux-headers-6.5.0-44, it is removed as a reverse dependency of it ("unwanted removal" does not check for running kernel)

- The KeepInstalledSection is also only respected at the initial skip, so an obsolete KeepInstalledSection package KIS is removed anyway if it depends on another obsolete package. Hooray.

We probably ought to fix these too.
-- 
https://code.launchpad.net/~juliank/ubuntu-release-upgrader/+git/ubuntu-release-upgrader/+merge/472686
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~juliank/ubuntu-release-upgrader:ubuntu/noble into ubuntu-release-upgrader:ubuntu/noble.