Modify various sim10 related slots

Modify build for powheg to add mr for decfiles in lhcb-gauss-gen-dev

Move to lhcb-sim10 boole and add dependency to LHCb v51r3. Put there Gauss v54r5 for now.

All other sim10 based slots, lhcb-gauss-gen-dev, lhcb-gauss-gen2-dev, lhcb-gauss-lamarr, lhcb-gauss-fast, lhcb-gauss-conf, as well as lhcb-gauss-dev are using Gauss HEAD to allow picking up specific MR via corresponding labels.

For now leave Gauss v54r4p1 in lhcb-sim10-ref, so that we could fix it and run LHCbPR test for referenced or the upgrade.