Deprecate Kubernetes 1.25, 1.26 in documentation
Summary
We have completed adding Kubernetes 1.29 support with Support deploying GitLab on Kubernetes 1.29 (gitlab-org/distribution/team-tasks#1473 - closed).
1.29 is already listed as supported at https://docs.gitlab.com/operator/installation.html#cluster, but we need to mark 1.25 and 1.26 as deprecated in that table.
Our k8s support policy https://handbook.gitlab.com/handbook/engineering/infrastructure/core-platform/systems/distribution/k8s-release-support-policy/#kubernetes-officially-supported-releases.
Edited by Dustin Collins