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/build/toolchain/musl-host-gcc/BUILD b/build/toolchain/musl-host-gcc/BUILD
index 95a59f6..561e311 100644
--- a/build/toolchain/musl-host-gcc/BUILD
+++ b/build/toolchain/musl-host-gcc/BUILD
@@ -3,8 +3,8 @@
 # This file defines //build/toolchain/musl-host-gcc:musl_host_cc_suite.
 #
 # This is a C++ toolchain that uses GCC from the host at hardcoded paths, with
-# a pre-built sysroot tarball that targets Smalltown with musl and Linux headers.
-# It's a superset of //build/toolchain:host_cc_suite.
+# a pre-built sysroot tarball that targets Metropolis nodes with musl and Linux
+# headers.  It's a superset of //build/toolchain:host_cc_suite.
 # For more information, see README.md.
 
 cc_toolchain_suite(