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

scripts/slave/recipe_modules/git_clone_bundler/example.expected/repo.json

 [
   {
     "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]/git_clone_bundler/bundles"
     ],
     "name": "rmtree old bundles",
     "~followup_annotations": [
@@ skipping 92 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]/git_clone_bundler/repo/baa8c54f5ad38fa45e904e6bdfb6b484/path/to/foo",
     "name": "create bundle (src/foo)"
   },
   {
     "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]/git_clone_bundler/bundles/b30c7a01edcf711e48356dd038d8c03e.bundle",
       "gs://clone-dot-bundle-bucket/checkout/repository/src/foo/clone.bundle"
     ],
     "name": "gsutil upload bundle (src/foo)",
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil bundle@https://storage.cloud.google.com/clone-dot-bundle-bucket/checkout/repository/src/foo/clone.bundle@@@"
     ]
   },
@@ skipping 21 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]/git_clone_bundler/repo/baa8c54f5ad38fa45e904e6bdfb6b484/path/to/bar",
     "name": "create bundle (src/bar)"
   },
   {
     "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]/git_clone_bundler/bundles/4e9dd63391c5eb1884b9b449679dfa16.bundle",
       "gs://clone-dot-bundle-bucket/checkout/repository/src/bar/clone.bundle"
     ],
     "name": "gsutil upload bundle (src/bar)",
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil bundle@https://storage.cloud.google.com/clone-dot-bundle-bucket/checkout/repository/src/bar/clone.bundle@@@"
     ]
   },
@@ skipping 10 matching lines @@
     "~followup_annotations": [
       "@@@STEP_TEXT@https://localhost/bar.git@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]