Skytap Linux/ppc64 capacity restricted due to Ubuntu being unavailable on POWER8

We were recently migrated from Skytaps's POWER9 in their Amsterdam data centre to older generation POWER8 systems. [Ubuntu 22.04+ does not support POWER8](https://ubuntu.com/download/server/power) and there is no template available for Ubuntu 20.04 in that location.

At the moment this means that many of our test-docker ppc64le machines are offline
Ref: https://ci.adoptium.net/label/hw.dockerhost.dockerhost-skytap-ubuntu2204-ppc64le-1/


Text list (excluding the one that's showing as online in the image above):

- [test-docker-debian11-ppc64le-1](https://ci.adoptium.net/computer/test%2Ddocker%2Ddebian11%2Dppc64le%2D1/)
- [test-docker-debian11-ppc64le-2](https://ci.adoptium.net/computer/test%2Ddocker%2Ddebian11%2Dppc64le%2D2/)
- [test-docker-debian11-ppc64le-3](https://ci.adoptium.net/computer/test%2Ddocker%2Ddebian11%2Dppc64le%2D3/)
- [test-docker-ubi8-ppc64le-1](https://ci.adoptium.net/computer/test%2Ddocker%2Dubi8%2Dppc64le%2D1/)
- [test-docker-ubi9-ppc64le-1](https://ci.adoptium.net/computer/test%2Ddocker%2Dubi9%2Dppc64le%2D1/)
- [test-docker-ubuntu2204-ppc64le-2](https://ci.adoptium.net/computer/test%2Ddocker%2Dubuntu2204%2Dppc64le%2D2/)
- [test-docker-ubuntu2404-ppc64le-1](https://ci.adoptium.net/computer/test%2Ddocker%2Dubuntu2404%2Dppc64le%2D1/)

Start with the linked CI label, machine pages, and Ubuntu POWER support page to confirm which listed ppc64le hosts are unavailable and why. Done means the affected test-docker hosts have a supported image and are back online, or the capacity limitation and replacement plan are documented.

Written by the indexing model from the issue text.