smalltown -> metropolis

This pass removes all mentions of Smalltown, both from code and comments,
and replaces them with appropriate new terminology.

Test Plan: Refactor, covered by CI.

X-Origin-Diff: phab/D674
GitOrigin-RevId: 04a94d44ef07d46f7821530da5614daefe16d7ea
diff --git a/metropolis/node/kubernetes/reconciler/resources_rbac.go b/metropolis/node/kubernetes/reconciler/resources_rbac.go
index 40ca879..15386a6 100644
--- a/metropolis/node/kubernetes/reconciler/resources_rbac.go
+++ b/metropolis/node/kubernetes/reconciler/resources_rbac.go
@@ -146,7 +146,7 @@
 					APIGroup: rbac.GroupName,
 					Kind:     "User",
 					// TODO(q3k): describe this name's contract, or unify with whatever creates this.
-					Name: "smalltown:apiserver-kubelet-client",
+					Name: "metropolis:apiserver-kubelet-client",
 				},
 			},
 		},