Update bzimage kernel image download path

[alxiord]

Summary of the PR

The integ tests used to download a 4.9 kernel image from the Debian servers, which has been since taken down. Updating to a 5.10 image and adjusting the tests accordingly.

Fixes #149

Requirements

Before submitting your PR, please make sure you addressed the following requirements:

• [x] All commits in this PR are signed (with git commit -s), and the commit message has max 60 characters for the summary and max 75 characters for each description line.
• [x] All added/changed functionality has a corresponding unit/integration test.
• [x] All added/changed public-facing functionality has entries in the "Upcoming Release" section of CHANGELOG.md (if no such section exists, please create one).
• [x] Any newly added unsafe code is properly documented.

[roypat]

Alright, so I had a quick look into why the CI is failing, and its due to how we collect criterion data. Since we don't check benchmark data into the repository, we run criterion twice: Once against main, and once on the actual PR. However, when checking out main, we try to download the now-removed ubuntu image, causing the failures. I don't think we have any alternative to just force-merging this PR :/

[andreeaflorescu]

Alright, so I had a quick look into why the CI is failing, and its due to how we collect criterion data. Since we don't check benchmark data into the repository, we run criterion twice: Once against main, and once on the actual PR. However, when checking out main, we try to download the now-removed ubuntu image, causing the failures. I don't think we have any alternative to just force-merging this PR :/

Right, this happened in the past as well, so we did force merges. Let's to this again.