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

scripts/slave/recipes/skia/swarm_trigger.expected/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Coverage-Trybot.json

 [
   {
     "cmd": [
       "git",
       "remote",
       "set-url",
       "origin",
       "https://skia.googlesource.com/skia.git"
     ],
     "cwd": "[SLAVE_BUILD]/skia",
@@ skipping 307 matching lines @@
       "0"
     ],
     "name": "Copy Go binary"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "help"
     ],
     "name": "gsutil help"
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
@@ skipping 422 matching lines @@
     "cwd": "[SLAVE_BUILD]/skia",
     "name": "git show",
     "stdout": "/path/to/tmp/"
   },
   {
     "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]/swarming_temp_dir/outputs/test_skia/0/164710.cov",
       "gs://skia-infra/coverage-raw-v1/trybot/2012/05/14/12/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Coverage-Trybot/5/500/164710.cov"
     ],
     "env": {
       "AWS_CREDENTIAL_FILE": null,
       "BOTO_CONFIG": null
     },
     "name": "gsutil upload raw coverage data",
@@ skipping 71 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@os.remove(sys.argv[1])@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "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]/swarming_temp_dir/outputs/test_skia/0/coverage_by_line_164710_1408633190.json",
       "gs://skia-infra/coverage-json-v1/trybot/2012/05/14/12/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Coverage-Trybot/5/500/coverage_by_line_164710_1408633190.json"
     ],
     "env": {
       "AWS_CREDENTIAL_FILE": null,
       "BOTO_CONFIG": null
     },
     "name": "gsutil upload line-by-line coverage data",
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil.upload@https://storage.cloud.google.com/skia-infra/coverage-json-v1/trybot/2012/05/14/12/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Coverage-Trybot/5/500/coverage_by_line_164710_1408633190.json@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]