proposal: consolidate smaller k8s clusters

Created by: keegancsmith

Here is the list of k8s clusters (that I have connected to):

• gke_sourcegraph-dev_us-central1-a_ci
• gke_sourcegraph-dev_us-central1-a_dogfood
• gke_sourcegraph-dev_us-central1-a_dogfood-full-k8s
• gke_sourcegraph-dev_us-central1-a_tooling
• gke_sourcegraph-dev_us-central1-f_dot-com

I would suspect we can consolidate all of them except dot-com. For the case of CI we can create a pool for the CI jobs so we can keep the auto scaling behaviour of the nodes. If that is too tricky, we should atleast consolidate the dogfood and tooling clusters.

WDYT? cc @ggilmore @sourcegraph/distribution