gsutil: use depot_tools.gsutil_py_path instead of path['depot_tools']

scripts/slave/recipes/v8.expected/full_client_v8_V8_Win32___debug_builder.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 221 matching lines @@
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]\\resources\\gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]\\gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gsutil.py",
       "----",
       "cp",
       "-a",
       "public-read",
       "{\"bot_default\": \"[dummy hash for bot_default]\", \"ignition\": \"[dummy hash for ignition]\", \"mozilla\": \"[dummy hash for mozilla]\", \"test262\": \"[dummy hash for test262]\"}",
       "gs://chromium-v8/v8-win32-dbg/full-build-win32_f2cbea7e89a45f46819777bb78a1f5bd0241f64c.json"
     ],
     "name": "gsutil upload",
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil.upload@https://storage.cloud.google.com/chromium-v8/v8-win32-dbg/full-build-win32_f2cbea7e89a45f46819777bb78a1f5bd0241f64c.json@@@"
@@ skipping 48 matching lines @@
     "~followup_annotations": [
       "@@@STEP_TEXT@V8 Win32 - debug@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]