Never use the hermetic xcode toolchain for iOS recipes.

scripts/slave/recipes/webrtc/ios.expected/no_tests.json

Index: scripts/slave/recipes/webrtc/ios.expected/no_tests.json
diff --git a/scripts/slave/recipes/webrtc/ios.expected/no_tests.json b/scripts/slave/recipes/webrtc/ios.expected/no_tests.json
index d5ca1821efa6e48ed906079c3d00658b6254d94b..59a5afe88e6025ae63e45bd303dd2d6c83ffee56 100644
--- a/scripts/slave/recipes/webrtc/ios.expected/no_tests.json
+++ b/scripts/slave/recipes/webrtc/ios.expected/no_tests.json
@@ -239,7 +239,6 @@
     ],
     "cwd": "[BUILDER_CACHE]/ios/src",
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "generate_build_files"
@@ -256,7 +255,6 @@
       "/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",
@@ -306,7 +304,6 @@
     ],
     "cwd": "[BUILDER_CACHE]/ios/src/out/Release-iphoneos",
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "compile",