Revert of Download the hermetic xcode toolchain on all bots that target mac.

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

Index: scripts/slave/recipes/chromium.expected/full_chromium_gpu_fyi_GPU_Mac_Builder.json
diff --git a/scripts/slave/recipes/chromium.expected/full_chromium_gpu_fyi_GPU_Mac_Builder.json b/scripts/slave/recipes/chromium.expected/full_chromium_gpu_fyi_GPU_Mac_Builder.json
index e7d258ae8d924f3d3134ea1dff5bf6b37a1717c2..b30e66b752cc3ffad1454a9ccf098d11521858b0 100644
--- a/scripts/slave/recipes/chromium.expected/full_chromium_gpu_fyi_GPU_Mac_Builder.json
+++ b/scripts/slave/recipes/chromium.expected/full_chromium_gpu_fyi_GPU_Mac_Builder.json
@@ -203,7 +203,6 @@
     ],
     "cwd": "[BUILDER_CACHE]/mac/src",
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
       "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_DEFINES": "archive_gpu_tests=1 clang=1 component=static_library ffmpeg_branding=Chrome gomadir='[CACHE]/cipd/goma' internal_gles2_conform_tests=1 proprietary_codecs=1 target_arch=x64 test_isolation_mode=prepare use_goma=1",
@@ -371,7 +370,6 @@
     ],
     "cwd": "[BUILDER_CACHE]/mac/src",
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "generate_build_files",
@@ -392,7 +390,6 @@
       "/path/to/tmp/json"
     ],
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "clang_revision",
@@ -445,7 +442,6 @@
       "browser_tests_run"
     ],
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "compile",