Labeling bisect/perf try jobs with a prominent null step.

scripts/slave/recipes/bisection/android_bisect.expected/local_basic_recipe_disconnected_device.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "tryserver.chromium.perf",
       "--builder",
       "android_one_perf_bisect",
@@ skipping 418 matching lines @@
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
       "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_CROSSCOMPILE": "1",
       "GYP_DEFINES": "OS=android component=static_library fastbuild=1 gomadir='[BUILD]/goma' target_arch=arm use_goma=1",
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
+    "cmd": [],
+    "name": "***BISECT***"
+  },
+  {
     "cmd": [
       "[SLAVE_BUILD]/src/third_party/catapult/devil/devil/android/tools/device_status.py",
       "--json-output",
       "/path/to/tmp/json",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json",
       "--known-devices-file",
       "[HOME]/.android/known_devices.json",
       "--buildbot-path",
       "/home/chrome-bot/.adb_device_info",
@@ skipping 3022 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@  os.remove(report)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]