Include timestamp in nanobench JSON file name

infra/bots/recipes/swarm_trigger.expected/Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-Trybot.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport json\nimport sys\n\nwith open(sys.argv[1]) as f:\n  content = json.load(f)\n\nprint json.dumps(content, indent=2)\n",
       "{\"buildername\": \"Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-Trybot\", \"buildnumber\": 5, \"issue\": 500, \"mastername\": \"client.skia\", \"patchset\": 1, \"path_config\": \"kitchen\", \"recipe\": \"swarm_trigger\", \"revision\": \"abc123\", \"rietveld\": \"https://codereview.chromium.org\", \"slavename\": \"skiabot-linux-swarm-000\"}"
     ],
     "name": "print properties",
     "~followup_annotations": [
@@ skipping 666 matching lines @@
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@STEP_LINK@shard #0@https://chromium-swarm.appspot.com/user/task/10000@@@",
       "@@@STEP_LINK@view steps on Milo@https://luci-milo.appspot.com/swarming/task/10000@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
-      "\nimport os, sys\nfrom common import chromium_utils # Error? See https://crbug.com/584783.\n\n\nif os.path.exists(sys.argv[1]):\n  chromium_utils.RemoveDirectory(sys.argv[1])\n",
-      "[SLAVE_BUILD]/swarming_temp_dir/outputs/perf_skia"
-    ],
-    "env": {
-      "PYTHONPATH": "[SLAVE_BUILD]/skia/infra/bots/.recipe_deps/build/scripts"
-    },
-    "name": "rmtree perf_skia",
-    "~followup_annotations": [
-      "@@@STEP_LOG_LINE@python.inline@@@@",
-      "@@@STEP_LOG_LINE@python.inline@import os, sys@@@",
-      "@@@STEP_LOG_LINE@python.inline@from common import chromium_utils # Error? See https://crbug.com/584783.@@@",
-      "@@@STEP_LOG_LINE@python.inline@@@@",
-      "@@@STEP_LOG_LINE@python.inline@@@@",
-      "@@@STEP_LOG_LINE@python.inline@if os.path.exists(sys.argv[1]):@@@",
-      "@@@STEP_LOG_LINE@python.inline@  chromium_utils.RemoveDirectory(sys.argv[1])@@@",
-      "@@@STEP_LOG_END@python.inline@@@"
-    ]
-  },
-  {
-    "cmd": [
-      "python",
-      "-u",
       "[SLAVE_BUILD]/swarming.client/swarming.py",
       "collect",
       "--swarming",
       "https://chromium-swarm.appspot.com",
       "--decorate",
       "--print-status-updates",
       "--json",
       "{\"base_task_name\": \"perf_skia/Ubuntu/def456/Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-Trybot/5\", \"tasks\": {\"perf_skia/Ubuntu/def456/Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-Trybot/5\": {\"shard_index\": 0, \"task_id\": \"10000\", \"view_url\": \"https://chromium-swarm.appspot.com/user/task/10000\"}}}",
       "--task-summary-json",
-      "/path/to/tmp/json",
-      "--task-output-dir",
-      "[SLAVE_BUILD]/swarming_temp_dir/outputs/perf_skia"
+      "/path/to/tmp/json"
     ],
     "name": "perf_skia on Ubuntu",
     "~followup_annotations": [
       "@@@STEP_TEXT@swarming pending 71s@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"shards\": [@@@",
       "@@@STEP_LOG_LINE@json.output@    {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"abandoned_ts\": null, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"bot_id\": \"vm30\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"completed_ts\": \"2014-09-25T01:42:00.123\", @@@",
@@ skipping 276 matching lines @@
       "@@@STEP_LINK@shard #0 isolated out@blah@@@",
       "@@@STEP_LINK@view steps on Milo@https://luci-milo.appspot.com/swarming/task/148aa78d7aa0000@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]