[madgraph2022 build ci-v0.7] harmonise test durations and support multi GPU archs

This includes fixes for

• harmonising test durations BMK-1056
• sleepa 100 seconds in 0.1 steps instead of 0.5 steps (reduce jitter BMK-1056)
• supporting multi-GPU-arch builds BMK-1060

It also reduces the verbosity of the sleep mechanism