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

scripts/slave/recipes/infra/depot_tools_builder.expected/basic.json

 [
   {
     "cmd": [],
     "name": "clean workspace"
   },
   {
     "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",
@@ skipping 156 matching lines @@
     ],
     "name": "zip it up",
     "stdin": "{\"entries\": [{\"path\": \"[SLAVE_BUILD]/depot_tools\", \"type\": \"dir\"}], \"output\": \"[SLAVE_BUILD]/depot_tools.zip\", \"root\": \"[SLAVE_BUILD]/depot_tools\"}"
   },
   {
     "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",
       "[SLAVE_BUILD]/depot_tools.zip",
       "gs://chrome-infra/depot_tools.zip"
     ],
     "name": "gsutil upload",
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil.upload@https://storage.googleapis.com/chrome-infra/depot_tools.zip@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "cp",
       "-r",
       "-z",
       "html",
       "-a",
       "public-read",
       "[SLAVE_BUILD]/depot_tools/man/html",
       "gs://chrome-infra-docs/flat/depot_tools/docs/"
     ],
     "name": "gsutil upload docs"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]