Ensure jaeger-related pods don't land in worker node pools

[cirocosta]

Despite us having added nodeSelector to values.yaml there (see fe870da), it seems like we didn't really do it right - looking at jaeger's pod, it's not really in a node from the generic-1 pool:

Node:           gke-hush-house-workers-3-687beb5a-cv4c/10.10.0.63

That is a problem as we've been considering the worker pools to be reserved only for Concourse workers as Concourse will take care of containers by itself.

We could do so by either ensuring that nodeSelector is really properly specified in the right way, or perhaps adopting a different pattern, leveraging taints and tolerations (https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/)