iOS: Update device testing configuration

The previous configuration committed in
https://codereview.webrtc.org/2903843002/
accidentally was tailored for running on simulator
swarming testers rather than device testers.

BUG=chromium:704912
NOTRY=True
TBR=smut@google.com

Review-Url: https://codereview.webrtc.org/2919783002
Cr-Commit-Position: refs/heads/master@{#18397}

tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64.json

@@ -5,20 +5,25 @@
   "xcode version": "8.0",
   "gn_args": [
     "goma_dir=\"$(goma_dir)\"",
+    "additional_target_cpus=[\"arm\"]",
     "is_component_build=false",
     "is_debug=true",
-    "target_cpu=\"x64\"",
+    "target_cpu=\"arm64\"",
     "target_os=\"ios\"",
     "use_goma=true"
   ],
+  "env": {
+    "MAC_TOOLCHAIN_REVISION": "8E2002-1"
+  },
   "use_analyze": false,
   "additional_compile_targets": [ "all" ],
   "configuration": "Debug",
+  "bucket": "chromium-webrtc",
   "tests": [
     {
-      "include": "common_tests.json",
+      "app": "modules_unittests",
       "device type": "iPhone 6s",
-      "os": "10.0"
+      "os": "10.0.1"
     }
   ]
 }