[nova] PTG schedule

Hi, I did a bit of reordering of the topics in the PTL etherpad[1] to move similar topics closer to each other. I did not try to assign specific timing to each topic. We will use the ptgbot during the PTG to notify the audience what we are talk about and what is the next topic. See you next week! Cheers, gibi [1]https://etherpad.opendev.org/p/nova-wallaby-ptg