Here are the little plugs I put on here, I hope this will work out okay, it was the best I have, and if this isn't a good permanent solution, it is a good temp cause it lights up just fine.
I use Fluorescent fixture quick connects on my power door luminaires. They work perfectly fine and can accommodate up to #12 stranded wire. Plus they're indexed so they can only go in one way.
This will work fine for you, just a little bulky. Like NiMo, I used those orange fluorescent light disconnects since they're more compact. If you used a 3-port one (I used two 2-port) you can share the "COM" on the line and lamp side of the ballast and get away with using one plug.
I usually use line voltage rated 4 pin Molex or similar connectors for my lights. You'll need a crimper to install though. I left a link on your other pic with more info.