Overrides taints on nodes

[mweibel]

👋 just a heads up on something we've been debugging: when running this controller and having nodes join using the register-with-taints flag, the taints get overridden and removed. We believe this is an issue with a lost update when doing the .Update call on a node. Not sure yet why exactly this is possible (given that the update should fail if the resource version is newer), but it's the case.