goma: back to build-provided client and disable oauth2

scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "chromium.webrtc",
       "--builder",
       "Mac Tester",
@@ skipping 96 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_v8_revision_cp@\"refs/heads/master@{#43426}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_swarming_client_revision_cp@\"refs/heads/master@{#276089}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_webrtc_revision_cp@\"refs/heads/master@{#120644}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_libvpx_revision_cp@\"refs/heads/master@{#11245}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#170242}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_libjingle_revision_cp@\"refs/heads/master@{#134440}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_angle_revision_cp@\"refs/heads/master@{#297276}\"@@@"
     ]
   },
   {
-    "cmd": [],
-    "cwd": "[SLAVE_BUILD]",
-    "name": "ensure_goma"
-  },
-  {
-    "cmd": [
-      "python",
-      "-u",
-      "RECIPE_MODULE[build::cipd]/resources/bootstrap.py",
-      "--platform",
-      "mac-amd64",
-      "--dest-directory",
-      "[SLAVE_BUILD]/cipd",
-      "--json-output",
-      "/path/to/tmp/json"
-    ],
-    "cwd": "[SLAVE_BUILD]",
-    "name": "ensure_goma.install cipd",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@",
-      "@@@STEP_TEXT@cipd instance_id: 40-chars-fake-of-the-package-instance_id@@@",
-      "@@@STEP_LOG_LINE@json.output@{@@@",
-      "@@@STEP_LOG_LINE@json.output@  \"executable\": \"[SLAVE_BUILD]/cipd/cipd\", @@@",
-      "@@@STEP_LOG_LINE@json.output@  \"instance_id\": \"40-chars-fake-of-the-package-instance_id\"@@@",
-      "@@@STEP_LOG_LINE@json.output@}@@@",
-      "@@@STEP_LOG_END@json.output@@@"
-    ]
-  },
-  {
-    "cmd": [
-      "[SLAVE_BUILD]/cipd/cipd",
-      "ensure",
-      "--root",
-      "[CACHE]/cipd/goma",
-      "--list",
-      "infra_internal/goma/client/mac-amd64 release",
-      "--json-output",
-      "/path/to/tmp/json",
-      "--service-account-json",
-      "/creds/service_accounts/service-account-goma-client.json"
-    ],
-    "cwd": "[SLAVE_BUILD]",
-    "name": "ensure_goma.ensure_installed",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@",
-      "@@@STEP_LOG_LINE@json.output@{@@@",
-      "@@@STEP_LOG_LINE@json.output@  \"result\": [@@@",
-      "@@@STEP_LOG_LINE@json.output@    {@@@",
-      "@@@STEP_LOG_LINE@json.output@      \"instance_id\": \"resolved-instance_id-of-release---------\", @@@",
-      "@@@STEP_LOG_LINE@json.output@      \"package\": \"infra_internal/goma/client/mac-amd64\"@@@",
-      "@@@STEP_LOG_LINE@json.output@    }@@@",
-      "@@@STEP_LOG_LINE@json.output@  ]@@@",
-      "@@@STEP_LOG_LINE@json.output@}@@@",
-      "@@@STEP_LOG_END@json.output@@@"
-    ]
-  },
-  {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
-      "GYP_DEFINES": "clang=1 component=static_library ffmpeg_branding=Chrome gomadir='[CACHE]/cipd/goma' proprietary_codecs=1 target_arch=x64 use_goma=1",
+      "GYP_DEFINES": "clang=1 component=static_library ffmpeg_branding=Chrome gomadir='[BUILD]/goma' proprietary_codecs=1 target_arch=x64 use_goma=1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/testing/scripts/get_compile_targets.py",
       "--output",
@@ skipping 227 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "remoting_unittests"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]