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

scripts/slave/recipes/flutter/flutter.expected/linux.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os, sys\nfrom common import chromium_utils # Error? See https://crbug.com/584783.\n\npath = sys.argv[1]\nif os.path.exists(path):\n  for p in (os.path.join(path, x) for x in os.listdir(path)):\n    if os.path.isdir(p):\n      chromium_utils.RemoveDirectory(p)\n    else:\n      os.unlink(p)\n",
       "[SLAVE_BUILD]"
     ],
     "name": "rmcontents everything",
     "~followup_annotations": [
@@ skipping 133 matching lines @@
       "PUB_CACHE": "[SLAVE_BUILD]/.pub-cache"
     },
     "name": "flutter build apk stocks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "cp",
       "[SLAVE_BUILD]/flutter/examples/stocks/build/app.apk",
       "gs://flutter_infra/flutter/deadbeef/examples/Stocks.apk"
     ],
     "env": {
       "ANDROID_HOME": "[SLAVE_BUILD]/flutter/dev/bots/android_tools",
       "PATH": "[SLAVE_BUILD]/flutter/bin:[SLAVE_BUILD]/flutter/bin/cache/dart-sdk/bin:%(PATH)s",
       "PUB_CACHE": "[SLAVE_BUILD]/.pub-cache"
     },
@@ skipping 15 matching lines @@
       "PUB_CACHE": "[SLAVE_BUILD]/.pub-cache"
     },
     "name": "flutter build apk flutter_gallery"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "cp",
       "[SLAVE_BUILD]/flutter/examples/flutter_gallery/build/app.apk",
       "gs://flutter_infra/flutter/deadbeef/examples/Gallery.apk"
     ],
     "env": {
       "ANDROID_HOME": "[SLAVE_BUILD]/flutter/dev/bots/android_tools",
       "PATH": "[SLAVE_BUILD]/flutter/bin:[SLAVE_BUILD]/flutter/bin/cache/dart-sdk/bin:%(PATH)s",
       "PUB_CACHE": "[SLAVE_BUILD]/.pub-cache"
     },
@@ skipping 14 matching lines @@
       "PUB_CACHE": "[SLAVE_BUILD]/.pub-cache"
     },
     "name": "dartdoc packages"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]