Upgrade k8s.io/* to v0.25, sigs.k8s.io/controller-runtime to v0.13

[rfranzke]

How to categorize this issue?

What would you like to be added:

We should upgrade to the latest versions of our go upstream dependencies:

• sigs.k8s.io/controller-runtime@v0.13.0: https://github.com/kubernetes-sigs/controller-runtime/releases/tag/v0.13.0
• k8s.io/*@v0.25.0

Important changes / Action items

Here is a list of a few upstream changes to look out for when vendoring g/g, k/* and c-r in any of our repos (e.g. extensions). Please consider the release notes of controller-runtime@v0.13 and upwards as well for a more complete list and more details.

⚠️ breaking / most notable changes

• Implement IgnoreAlreadyExists (✨ Implement IgnoreAlreadyExists kubernetes-sigs/controller-runtime#1965), i.e. we can drop

  gardener/pkg/utils/kubernetes/kubernetes.go

  Lines 638 to 643 in 5f7fff0

  	func IgnoreAlreadyExists(err error) error {
  	if apierrors.IsAlreadyExists(err) {
  	return nil
  	}
  	return err
  	}

• webhook: add an option to recover from panics in handler (✨ webhook: add an option to recover from panics in handler kubernetes-sigs/controller-runtime#1900)

ℹ️ other changes / good to know / for information only:

• Add GetOptions as optional argument of client.Reader and all its implementation (⚠ Add GetOptions as optional argument of client.Reader and all its implementation kubernetes-sigs/controller-runtime#1917)