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/test/e2e/main_test.go b/metropolis/test/e2e/main_test.go
index 46e862c..75b96b7 100644
--- a/metropolis/test/e2e/main_test.go
+++ b/metropolis/test/e2e/main_test.go
@@ -52,7 +52,7 @@
 	largeTestTimeout = 120 * time.Second
 )
 
-// TestE2E is the main E2E test entrypoint for single-node freshly-bootstrapped E2E tests. It starts a full Smalltown node
+// TestE2E is the main E2E test entrypoint for single-node freshly-bootstrapped E2E tests. It starts a full Metropolis node
 // in bootstrap mode and then runs tests against it. The actual tests it performs are located in the RunGroup subtest.
 func TestE2E(t *testing.T) {
 	// Run pprof server for debugging