test_runner: fix duration_ms to be milliseconds

PR-URL: #44450
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>

Author: MoLow

lib/internal/test_runner/test.js

@@ -615,8 +615,8 @@ class Test extends AsyncResource {
   }
 
   #duration() {
-    // Duration is recorded in BigInt nanoseconds. Convert to seconds.
-    return Number(this.endTime - this.startTime) / 1_000_000_000;
+    // Duration is recorded in BigInt nanoseconds. Convert to milliseconds.
+    return Number(this.endTime - this.startTime) / 1_000_000;
   }
 
   report() {