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

scripts/slave/recipes/bisection/desktop_bisect.expected/basic_linux_bisect_tester_recipe.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "tryserver.chromium.perf",
       "--builder",
       "linux_perf_bisect",
@@ skipping 177 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]/src",
     "name": "git diff to analyze patch",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@files@foo.cc@@@",
       "@@@STEP_LOG_END@files@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "***SINGLE TEST (deprecated)***"
+  },
+  {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::bisect_tester]/resources/put_temp.py"
     ],
     "name": "saving url to temp file",
     "stdin": "http://build.chromium.org/p/tryserver.chromium.perf/json/builders/linux_perf_bisect/builds/571",
     "stdout": "/path/to/tmp/"
   },
   {
@@ skipping 151 matching lines @@
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil.upload@https://storage.cloud.google.com/chrome-perf/bisect-results/f7a7b4135624439cbd27fdd5133d74ec.results@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]