tools: enable no-unused-expressions lint rule

Fixes: https://github.com/nodejs/node/issues/36246

PR-URL: https://github.com/nodejs/node/pull/36248
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

benchmark/string_decoder/string-decoder-create.js

@@ -12,8 +12,7 @@ const bench = common.createBenchmark(main, {
 function main({ encoding, n }) {
   bench.start();
   for (let i = 0; i < n; ++i) {
-    const sd = new StringDecoder(encoding);
-    !!sd.encoding;
+    new StringDecoder(encoding);
   }
   bench.end(n);
 }