Revert "Connectivity deprecation fix"

This reverts commit 7d62e8c which landed on the wrong branch.

Author: collinjackson

packages/connectivity/connectivity/android/src/main/java/io/flutter/plugins/connectivity/ConnectivityBroadcastReceiver.java

@@ -33,7 +33,7 @@ class ConnectivityBroadcastReceiver extends BroadcastReceiver
   @Override
   public void onListen(Object arguments, EventChannel.EventSink events) {
     this.events = events;
-    context.registerReceiver(this, new IntentFilter(ConnectivityManager.CONNECTIVITY_CHANGE));
+    context.registerReceiver(this, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
   }
 
   @Override

packages/connectivity/connectivity/lib/connectivity.dart

@@ -33,8 +33,6 @@ class Connectivity {
   static ConnectivityPlatform get _platform => ConnectivityPlatform.instance;
 
   /// Fires whenever the connectivity state changes.
-  ///
-  /// Apps targeting Android N do not receive notifications in the background.
   Stream<ConnectivityResult> get onConnectivityChanged {
     return _platform.onConnectivityChanged;
   }