LOW-261: clean up and modernise charts role
Prompted by adding a new node to PSI Low, resurrecting an old branch with a few improvements.
- Primarily, this deploys ingress-nginx and kube-state-metrics using Helm, which allows their deployments to be more easily customised by users of the role. The current ingress-nginx chart contains the fixes we were previously applying manually.
- Replace manual templating of apt source files with the
apt_repository
module. - Replace some instances of
when
withrun_once
+delegate
. This helps when you're targeting a single node using--limit
. - A few vars cleaned up and a couple other small tweaks.