Switch to Alpine images for Docker build

[Project board link](https://github.com/orgs/k8ssandra/projects/8/views/1?pane=issue&itemId=117030621)



┆Issue is synchronized with this [Jira Story](https://datastax.jira.com/browse/MED-136) by [Unito](https://www.unito.io)
┆Issue Number: MED-136
