refactor: bump golangci-lint to 2.6.2

[bernot-dev]

Bump golangci-lint to 2.6.2.

The removals of omitempty in json struct tags have been verified by modernize to be ineffective. omitzero was not added to avoid behavior changes. Corresponding fields have been explicitly marked optional. This results in some updates to the documentation, but no changes to the CRDs themselves.

Instances of interface{} have been changed to any.

String formatting functions have been replaced when they do not use actual formatting placeholders.

TestMain implicitly calls os.Exit since 1.15.

The pattern of splitting and then iterating over the parts has been replaced with SplitSeq, which is more efficient.

[bwplotka]

Thanks! Majority changes make sense, just few suggestions.

The removals of omitempty in json struct tags have been verified by modernize to be ineffective. omitzero was not added to avoid behavior changes. Corresponding fields have been explicitly marked optional. This results in some updates to the documentation, but no changes to the CRDs themselves.

Hm, are we sure about the modernize check? This is true for std json, but we don't use std json decoding but that yaml.v3 which does have a unique omitempty-almost-like-omitzero behaviour - https://pkg.go.dev/gopkg.in/yaml.v3#section-readme:~:text=Only%20include%20the%20field%20if%20it%27s%20not%20set%20to%20the%20zero

Notably zero value is omitted in our yaml parsing (also what k8s is using) (!), so I think this can potentially break things. Can we ignore that modernize rule just to be safe (unless we have time to test this thoroughly)?