test: run misc benchmark only once in tests

Prevent misc benchmark files from running more than one benchmark
during tests.

PR-URL: nodejs#21046
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

benchmark/misc/util-extend-vs-object-assign.js

@@ -9,6 +9,10 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, type }) {
+  // Default value for tests.
+  if (type === '')
+    type = 'extend';
+
   let fn;
   if (type === 'extend') {
     fn = util._extend;

test/parallel/test-benchmark-misc.js

@@ -9,6 +9,6 @@ runBenchmark('misc', [
   'dur=0.1',
   'method=',
   'n=1',
-  'type=extend',
-  'val=magyarország.icom.museum'
+  'type=',
+  'val=magyarország.icom.museum',
 ], { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });