landscape auto-upgrade is not cluster aware

When investigating a recent issue on our percona-cluster database, we found that the three nodes of our HA cluster environment randomly got scheduled for patching at 14:06, 14:12, and 14:12. During the patching of the first node, the database shutdown for the percona-cluster patch upgrade scripts hung indefinitely, and the other two nodes patched (along with restarts) before the first node completed patching. This condition turned into losing all three instances of the database because the startup failed on the second and third nodes because the first node hung up.

I'd like to request a feature upgrade for landscape or it's client to detect if there's a peer hacluster or "crm" installation on the landscape-client-charm unit and determine some way to lock out cluster neighbors from updating at the same time. I realize in our particular scenario, the fault was on the percona/mysql instance, but the entire cluster outage was caused by "random offset" creating a race condition where the failed mysql instance couldn't be detected before the other nodes started upgrading, and two nodes upgraded at the same time, even through random selection.