tests: re-activate the graceful leave tests under load
tests: re-activate the graceful leave tests under load

Graceful leaves of up to 3 nodes are supported since an RTM should take over in this case. If 4 or more leave, there may be no TM/RTM left to continue the transaction!
digshock/scalaris,digshock/scalaris,tectronics/scalaris,tectronics/scalaris,digshock/scalaris,tectronics/scalaris,seyyed/scalaris,seyyed/scalaris,digshock/scalaris,tectronics/scalaris,seyyed/scalaris,seyyed/scalaris,digshock/scalaris,tectronics/scalaris,seyyed/scalaris,tectronics/scalaris,seyyed/scalaris,digshock/scalaris,tectronics/scalaris,digshock/scalaris,seyyed/scalaris