Adds a note on upgrade_eks_nodegroups in the Dedicated toil template
What
It adds a note in the Dedicated upgrade toil issue, notifying the SREs on-call about the status of https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/issues/6380+
Why
It provides some context on what the EoC can expect in next week's maintenance upgrade.
Related to: https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/issues/6380#note_2161135381