Go 1.25 comes with a major improvment for Kubernetes, it now reads the cgroup CPU limits set in the container and automatically adjusts GOMAXPROCS. This means we can drop GOMAXPROCS from the distribution manifests that are now using the downward API.

To Go upgrade procedure is:

1. Bump the go minor version in all go.mod files.
2. Change the Makefile tidy target to match the new Go version.
3. Bump the golang image tag in Dockerfiles (including Go fuzzing).
4. Bump the go-version in all GitHub workflows.
5. Bump the Go version in Prerequisites section of all dev docs.

Repos subject to this upgrade:

• cli-utils
• pkg
• go-git-providers
• source-controller
• kustomize-controller
• notification-controller
• helm-controller
• image-reflector-controller
• image-automation-controller
• flux2
• terraform-provider-flux

Note that releasing cli-utils, then all fluxcd/pkg with Go 1.25 must be done before moving to controllers.