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/clusternet/clusternet.go b/metropolis/node/kubernetes/clusternet/clusternet.go
index d8dc7ad..cd78434 100644
--- a/metropolis/node/kubernetes/clusternet/clusternet.go
+++ b/metropolis/node/kubernetes/clusternet/clusternet.go
@@ -52,7 +52,7 @@
 
 const (
 	clusterNetDeviceName = "clusternet"
-	publicKeyAnnotation  = "node.smalltown.nexantic.com/wg-pubkey"
+	publicKeyAnnotation  = "node.metropolis.monogon.dev/wg-pubkey"
 )
 
 type Service struct {