cluster/kube: limit OSDs in ceph-waw3 to 8GB RAM

Each OSD is connected to a 6TB drive, and with the good ol' 1TB storage
-> 1GB RAM rule of thumb for OSDs, we end up with 6GB. Or, to round up,
8GB.

I'm doing this because over the past few weeks OSDs in ceph-waw3 have
been using a _ton_ of RAM. This will probably not prevent that (and
instead they wil OOM more often :/), but it at will prevent us from
wasting resources (k0 started migrating pods to other nodes, and running
full nodes like that without an underlying request makes for a terrible
draining experience).

We need to get to the bottom of why this is happening in the first
place, though. Did this happen as we moved to containerd?

Followup: b.hswaw.net/29

Already deployed to production.

Change-Id: I98df63763c35017eb77595db7b9f2cce71756ed1

cluster/kube/k0.libsonnet

@@ -97,6 +97,19 @@ local rook = import "lib/rook.libsonnet";
                         count: 1,
                         allowMultiplePerNode: false,
                     },
+                    resources: {
+                        osd: {
+                            requests: {
+                                cpu: "2"
+                                memory: "6G"
+                            },
+                            limits: {
+                                cpu: "2"
+                                memory: "8G"
+                            },
+                        },
+
+                    },
                     storage: {
                         useAllNodes: false,
                         useAllDevices: false,