TOOL-27512 LTS 24.04: Stop using HWE kernels when fetching kernel versions

[palash-gandhi]

Problem

check-updates jobs have been failing since 02/28 while checking updates for linux-kernel-generic with:

20:24:56  Running: git remote add upstream https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/noble
20:24:56  Running: get_kernel_version_for_platform_from_apt generic
20:24:57  note: upstream tag prefix used: Ubuntu-6.11-6.11.0-17
20:24:59  tag with prefix Ubuntu-6.11-6.11.0-17 not found.
20:24:59  trying tag prefix: Ubuntu-6.11.0-17.
20:25:01  Error: could not find upstream tag for tag prefix: Ubuntu-6.11.0-17

This logic looks for HWE kernels for the generic flavor and thus tries to use the same version as the HWE flavor. We do not need the HWE flavor.
Also note that all the jobs before 02/28 inferred the kernel version 6.8 for linux-kernel-generic, so this change ensures that we go back to the inferring the same version.

6.11 was released with 24.10. I suspect Canonical made 6.11 available on 24.04 via the HWE image. As to why we no longer need it, we relied on the HWE image as part of the 5.15 kernel upgrade. That was a one-off project, 20.04 shipped with 5.4 but we now wanted 5.15 so we started using HWE. That's no longer the case with 24.04 though, we do not need to jump to 6.11
This is a recent upstream change: https://www.phoronix.com/news/Ubuntu-24.04.2-LTS#:~:text=2%20LTS%20Now%20Available%20With%20Initial%20HWE%20Stack,-Written%20by%20Michael&text=Following%20last%20week's%20delay%20due,04.2%20updates%20too.

Solution

Modify the logic to not use the HWE flavor.

Testing Done

https://ops-jenkins.eng-tools-prd.aws.delphixcloud.com/job/linux-pkg/job/os-upgrade/job/check-updates/job/main/162/console

09:17:40  Running: get_kernel_version_for_platform_from_apt generic
09:17:40  note: upstream tag prefix used: Ubuntu-6.8-6.8.0-54
09:17:42  tag with prefix Ubuntu-6.8-6.8.0-54 not found.
09:17:42  trying tag prefix: Ubuntu-6.8.0-54.
09:17:43  Running: git fetch upstream +refs/tags/Ubuntu-6.8.0-54.56:refs/tags/Ubuntu-6.8.0-54.56

[jwk404]

Should the reference in default-package-config.sh also go?

[palash-gandhi]

Should the reference in default-package-config.sh also go?

On the os-upgrade branch, that reference was removed in a previous commit: d509765#diff-73f2a93c10bdc95bd270d7a0ea402b5430615c823cb83404f01acd5be354b8b5. I forgot to remove this one at the time and didn't surface until now because the HWE and regular images both had 6.8.