Switch to patch based updates

[staticf0x]

This PR will allow us to update Renovate version more easily (and even automatically using Renovate itself!).

• Both RENOVATE_VERSION and NODEJS_VERSION will be updated by Renovate, we'll only have to check if the NodeJS version fits the package.json contraints (couldn't figure out how to make the constraints)
• Instead of a branch forked off from https://github.com/redhat-exd-rebuilds/renovate we'll apply patches on top of https://github.com/[renovatebot/renovate](https://github.com/renovatebot/renovate)
  • This also means our fork is no longer necessary for building this image (it's still useful for code reviews though)

[querti]

How does this approach handle conflicts? I feel like we could end up with a broken instance if we just blindly applied patches without testing.

[staticf0x]

The build will fail if there's a conflict