Revert unconditional CATransaction. (#45454)

Cherry pick of fix for flutter/flutter#133147

shell/platform/darwin/ios/ios_surface_metal_impeller.mm

@@ -59,7 +59,7 @@
   // When there are platform views in the scene, the drawable needs to be presented in the same
   // transaction as the one created for platform views. When the drawable are being presented from
   // the raster thread, there is no such transaction.
-  layer.presentsWithTransaction = YES;
+  layer.presentsWithTransaction = [[NSThread currentThread] isMainThread];
 
   return layer;
 }