Remove mb_config Ozone platform arguments.

tools/mb/mb_config.pyl

Index: tools/mb/mb_config.pyl
diff --git a/tools/mb/mb_config.pyl b/tools/mb/mb_config.pyl
index a845aedcc1e1c34ea2b648941fcd887c582e597c..bac607862186324d66fe3a0418eb0f4133ddf6da 100644
--- a/tools/mb/mb_config.pyl
+++ b/tools/mb/mb_config.pyl
@@ -1035,11 +1035,11 @@
     ],
 
     'chromeos_with_codecs_ozone_release_bot': [
-      'chromeos_with_codecs', 'ozone', 'default_ozone_platform_x11', 'release_bot',
+      'chromeos_with_codecs', 'ozone', 'release_bot',
     ],
 
     'chromeos_with_codecs_ozone_release_trybot': [
-      'chromeos_with_codecs', 'ozone', 'default_ozone_platform_x11', 'release_trybot',
+      'chromeos_with_codecs', 'ozone', 'release_trybot',
     ],
 
     'chromeos_with_codecs_release_bot': [
@@ -1681,10 +1681,6 @@
       'mixins': ['debug_bot', 'minimal_symbols'],
     },
 
-    'default_ozone_platform_x11': {
-      'gn_args': 'ozone_platform="x11"',
-    },
-
     'disable_nacl': {
       'gn_args': 'enable_nacl=false',
     },