Workflow to delete old AMIs

[richardcase]

/kind feature

Describe the solution you'd like

Create a periodic GHA workflow that will delete AMIs that the project no longer supports.

Anything else you would like to add: [Miscellaneous information that will assist in solving the issue.]

Environment:

• Cluster-api-provider-aws version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

[richardcase]

/assign /triage accepted /priority important-soon

[richardcase]

I have some code for this already and so will pick it up.