Make CI tests run with ROCm 5

ROCm 5.0.0 has been available since some time. It would be good to move to the newer compiler offered by AMD, especially given its better C++ compatibility.

The following tasks need to be done to accomplish this issue:

• Make ROCm 5 repositories available in Online (thanks @ksawczuk !).
• Install ROCm 5 in n4051701 and test it works.
• Make Allen compatible with ROCm 5 (see !811 (closed)).
• Install ROCm 5 in CVMFS.
• Move CI to using it.