☂️ Drop support for Shoots with K8s < 1.17

[ialidzhikov]

How to categorize this issue?

/kind cleanup
/platform aws

What would you like to be added:
Since v1.40.0 Gardener no longer supports Shoots with K8s < 1.17. We can clean up similarly the provider extension to no longer have handlings for K8s < 1.17.

Extensions that need to be adapted:

• https://github.com/gardener/gardener-extension-provider-alicloud -> Vendor gardener/gardener@v1.40.2 gardener-extension-provider-alicloud#442
• https://github.com/gardener/gardener-extension-provider-aws -> Removes support for kubernetes < 1.17 for AWS extension provider #610
• https://github.com/gardener/gardener-extension-provider-gcp -> Removes support for Кubernetes < 1.17 for GCP extension provider gardener-extension-provider-gcp#493
• https://github.com/gardener/gardener-extension-provider-azure -> Remove support for kubernetes < 1.17 for Azure extension provider gardener-extension-provider-azure#573
• https://github.com/gardener/gardener-extension-provider-openstack -> Removes support for kubernetes < 1.17 for OpenStack extension provider gardener-extension-provider-openstack#496
• https://github.com/gardener/gardener-extension-networking-calico -> Removed support for outdated kubernetes releases. gardener-extension-networking-calico#150
• https://github.com/gardener/gardener-extension-networking-cilium -> Remove support for kubernetes < 1.17 for kube-proxy. gardener-extension-networking-cilium#127
• https://github.com/gardener/gardener-extension-runtime-gvisor -> Remove support for Shoots with Kubernetes version < 1.17 gardener-extension-runtime-gvisor#63
• Remove K8s < 1.17 from https://github.com/kubernetes/test-infra -> Clean up K8s 1.16 dashboards for Gardener kubernetes/test-infra#27576

Why is this needed:
Remove code that we no longer need.

[ialidzhikov]

/close
as all subtasks are resolved