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

scripts/slave/recipe_modules/auto_bisect/example.expected/failed_build_test.json

 [
   {
     "cmd": [
       "git",
       "update-ref",
       "refs/heads/master",
       "refs/remotes/origin/master"
     ],
     "cwd": "[TMP_BASE]/fake_checkout_tmp_1",
     "name": "git update-ref"
@@ skipping 136 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",
       "----",
       "ls",
       "gs://chrome-perf/Linux Builder/full-build-linux_a6298e4afedbf2cd461755ea6f45b0ad64222222.zip"
     ],
     "name": "gsutil ls",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
@@ skipping 17 matching lines @@
     ],
     "cwd": "[TMP_BASE]/fake_checkout_tmp_1",
     "name": "Requesting build for a6298e4afedbf2cd461755ea6f45b0ad64222222 via git try."
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "ls",
       "gs://chrome-perf/Linux Builder/full-build-linux_00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111.zip"
     ],
     "name": "gsutil ls (2)",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
@@ skipping 17 matching lines @@
     ],
     "cwd": "[TMP_BASE]/fake_checkout_tmp_1",
     "name": "Requesting build for 00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111 via git try."
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "ls",
       "gs://chrome-perf/Linux Builder/full-build-linux_a6298e4afedbf2cd461755ea6f45b0ad64222222.zip"
     ],
     "name": "gsutil ls (3)",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
@@ skipping 18 matching lines @@
       "/path/to/tmp/"
     ],
     "name": "fetch build details"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "ls",
       "gs://chrome-perf/Linux Builder/full-build-linux_00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111.zip"
     ],
     "name": "gsutil ls (4)"
   },
   {
     "cmd": [],
     "name": "Triggering test job for 00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111",
     "trigger_specs": [
@@ skipping 32 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@sys.exit(0)@@@",
       "@@@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",
       "----",
       "ls",
       "gs://chrome-perf/bisect-results/00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111-test.results"
     ],
     "name": "gsutil ls (5)"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::gsutil]/resources/gsutil_wrapper.py",
       "--",
-      "[DEPOT_TOOLS]/gsutil.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "----",
       "cat",
       "gs://chrome-perf/bisect-results/00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111-test.results"
     ],
     "name": "gsutil Get test results for build 00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111",
     "stdout": "/path/to/tmp/"
   },
   {
     "cmd": [
       "git",
       "footers",
       "--position",
       "00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111"
     ],
     "cwd": "[TMP_BASE]/fake_checkout_tmp_1",
     "name": "resolving hash 00316c9ddfb9d7b4e1ed2fff9fe6d964d2111111",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
       "@@@SET_BUILD_PROPERTY@extra_result_code@[\"B4T_TEST_FAILURE\"]@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]