Abort removing account if prohibited by policy

Bug: 13077993

If an EDU device was marked as prohibited from adding/removing accounts, it was throwing
an error but still continuing to remove the account. This fixes the problem by aborting
the removeAccount steps.

Change-Id: Ie7f157c5397a7391aab6f37c8a4331479f1b451b

services/core/java/com/android/server/accounts/AccountManagerService.java

@@ -863,6 +863,7 @@ public class AccountManagerService
                         "User cannot modify accounts");
             } catch (RemoteException re) {
             }
+            return;
         }
 
         long identityToken = clearCallingIdentity();