automated: linux: 24h-stress-test: fix git repository

[RamiGspo]

The repository is not found:

$ git clone git://kernel.ubuntu.com/cking/stress-ng.git
Klone nach 'stress-ng' …
fatal: Fehler am anderen Ende: no such repository: /cking/stress-ng.git

The test works after this change:

$ git clone git://kernel.ubuntu.com/ubuntu/stress-ng.git
Klone nach 'stress-ng' …
remote: Counting objects: 41543, done.
remote: Compressing objects: 100% (9594/9594), done.
remote: Total 41543 (delta 32120), reused 41338 (delta 31915)
Empfange Objekte: 100% (41543/41543), 17.71 MiB | 12.17 MiB/s, fertig.
Löse Unterschiede auf: 100% (32120/32120), fertig.

[roxell]

The ubuntu/stress-ng.git haven't been updated in a long time, looks like this is the place to clone it form
https://github.com/ColinIanKing/stress-ng

Can you please update the changelog too. basically say what you said in the PR message.