Fix failing assert in EventTarget

Summary:
changelog: [internal]

calling `setEnabled(true)` needs to have a matching `setEnabled(false)` in order for `eventTarget_` to be deallocated correctly.

Also, retaining `eventTarget_` longer, does not mean instanceHandle will be available later on.

Reviewed By: p-sun

Differential Revision: D31503119

fbshipit-source-id: 324e16fe0f6ad937ab2c38be9a536bdf14851172

React/Fabric/Mounting/ComponentViews/Modal/RCTModalHostViewComponentView.mm

@@ -156,9 +156,6 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
                        auto eventEmitter = [self modalEventEmitter];
                        if (eventEmitter) {
                          eventEmitter->onShow(ModalHostViewEventEmitter::OnShow{});
-
-                         // A hack so that EventEmitter.cpp's eventTarget_ does not become null when modal is dismissed
-                         eventEmitter->setEnabled(true);
                        }
                      }];
   }