Build: Add --clean (#12186)

scripts/release/steps/generate-bundles.js

@@ -2,7 +2,10 @@ import chalk from "chalk";
 import { runYarn, logPromise, readJson } from "../utils.js";
 
 export default async function generateBundles({ version }) {
-  await logPromise("Generating bundles", runYarn(["build"]));
+  await logPromise(
+    "Generating bundles",
+    runYarn(["build", "--clean", "--print-size"])
+  );
 
   const builtPkg = await readJson("dist/package.json");
   if (builtPkg.version !== version) {