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

scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_mac_swarming.json

Index: scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_mac_swarming.json
diff --git a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_mac_swarming.json b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_mac_swarming.json
index e02e492e5cb2ac9e3bbcbf7fef7bf2572ac7736e..8df26a8a0d919d409a08d35a9c9ac22f4e6209e2 100644
--- a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_mac_swarming.json
+++ b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_mac_swarming.json
@@ -198,7 +198,6 @@
     ],
     "cwd": "[BUILDER_CACHE]/mac_swarming/src",
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
       "GYP_DEFINES": "clang=1 component=shared_library dcheck_always_on=1 fastbuild=1 ffmpeg_branding=Chrome gomadir='[CACHE]/cipd/goma' rtc_use_h264=1 target_arch=x64 test_isolation_mode=prepare use_goma=1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
@@ -239,7 +238,6 @@
     ],
     "cwd": "[BUILDER_CACHE]/mac_swarming/src",
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "generate_build_files",
@@ -276,7 +274,6 @@
       "/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",
@@ -326,7 +323,6 @@
       "--"
     ],
     "env": {
-      "FORCE_MAC_TOOLCHAIN": "1",
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "compile",