[Android] Switch the x86, x64, and mips builders on chromium.android to mb.

scripts/slave/recipe_modules/amp/example.expected/slow_tests_basic.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]/gsutil.py",
       "----",
       "cp",
@@ skipping 92 matching lines @@
       "--test-apk",
       "TestApk.apk",
       "--isolate-file-path",
       "isolate_file.isolate",
       "--annotation",
       "SmallTest",
       "--additional-apk",
       "ExtraApk1.apk",
       "--additional-apk",
       "ExtraApk2.apk",
+      "--timeout-scale",
+      "10",
       "--enable-platform-mode",
       "-e",
       "remote_device",
       "--api-key-file",
       "[BUILD]/site_config/.amp_main_pool_key",
       "--api-secret-file",
       "[BUILD]/site_config/.amp_main_pool_secret",
       "--api-address",
       "127.0.0.1",
       "--api-port",
       "80",
       "--api-protocol",
       "http",
       "--device-type",
       "Android",
       "--remote-device",
       "SampleDevice",
       "--remote-device-os",
       "SampleDeviceOS",
       "--network-config",
       "8",
+      "--test-timeout",
+      "3600",
       "--trigger",
       "/path/to/tmp/json",
       "--verbose"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] example_instrumentation_suite",
     "~followup_annotations": [
       "@@@STEP_TEXT@on Foo Fone 1.2.3@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"env\": {@@@",
@@ skipping 402 matching lines @@
     "~followup_annotations": [
       "@@@STEP_LINK@logcat@https://storage.cloud.google.com/chrome-amp-results/logcats/logcat_example_uirobot_suite_T35TRUN1D.txt@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]