test: fix flaky test-benchmark-es

Allow zero iterations for short benchmark in test.

PR-URL: https://github.com/nodejs/node/pull/17516
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-benchmark-es.js

@@ -15,4 +15,5 @@ runBenchmark('es',
                'n=1',
                'encoding=ascii',
                'size=1e1'
-             ]);
+             ],
+             { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });