In HIVE-2616, while upgrading hive to use k8s 1.31, it was necessary to pull in controller-gen v0.16 (we ended up using v0.16.1). Prior to that PR we were getting our controller-gen binary via build-machinery-go, which grabbed it from the openshift fork of the controller-tools repo. But that fork hasn't been updated in a while, and specifically doesn't have the code or release or binaries for v0.16; so that PR bypasses BMG entirely and grabs the controller-gen binary from the upstream controller-tools repo. However, it does it in a kind of dumb and messy way.

We need to decide whether we want to continue using build-machinery-go for controller-gen. If so, we must:

• Wait for (but probably drive) https://github.com/openshift/build-machinery-go/issues/93
• Revert the Makefile piece of https://github.com/openshift/hive/pull/2477

If not, we should clean up the Makefile piece of https://github.com/openshift/hive/pull/2477 to be more

• cache-y: right now it always pulls the controller-gen binary
• file system pathing agnostic: right now it assumes the above installs at $GOPATH/bin (because I think we can't rely on $GOBIN to be set)