Update kubectl image to use kubectl 1.25.x

Summary

Update the kubectl version to 1.25.x

kubectl 1.24 has stopped receiving security updates at the end of July https://kubernetes.io/releases/patch-releases/#non-active-branch-history

But still sometimes gets high CVE backports. The latest at the moment of creating this issue was in August 2023 with kubectl 1.24.17. But there has been newer patch releases of 1.25 to fix medium golang security updates.

Tasks

• Update kubectl to 1.25
• Confirm chart' shared secrets job with new image works on a k3s 1.19 cluster (with the adjusted nginx-ingress tag https://gitlab.com/gitlab-org/charts/gitlab/-/blob/master/doc/installation/cloud/index.md#cloud-provider-setup-for-the-gitlab-chart) and if not, determine the new minium supported k8s version for the chart with this change, and update the chart documentation.