Crossbench: use file server to run Speedometer

Already using file server on Android. Expanding it to
desktop as well.

Change-Id: Ieccee4cbf7c6fe9ecff6b1ec4693ae04f0504336
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6035892
Commit-Queue: John Chen <johnchen@chromium.org>
Reviewed-by: Farid (Mojtaba) Faridzad <faridzad@google.com>
Cr-Commit-Position: refs/heads/main@{#1388917}

Author: JohnChen0

testing/scripts/run_performance_tests.py

@@ -735,9 +735,8 @@ def _get_network_arg(self, args):
       return self._create_fileserver_network(_arg)
     if self._get_arg(args, '--wpr'):
       return self._create_wpr_network(args)
-    if (self.is_android
-        and self.options.benchmarks in self.BENCHMARK_FILESERVERS):
-      # --fileserver is required in this case. Supply it.
+    if self.options.benchmarks in self.BENCHMARK_FILESERVERS:
+      # Use file server when it is available.
       arg = '--fileserver'
       args.append(arg)
       return self._create_fileserver_network(arg)