INT-3916: Don't Use CTOR Injection in FactoryBean

JIRA: https://jira.spring.io/browse/INT-3916

The `JpaOutboundGatewayFactoryBean` used CTOR injection for the `JpaExecutor`.
That one, in turn, uses CTOR injection for the `EntityManagerFactory`.

Such a dependency may cause the `early bean instantiating` in case of `AbstractAutowireCapableBeanFactory.getSingletonFactoryBeanForTypeCheck()`.
And we end up with the `BeanCurrentlyInCreationException`.

Therefore no one `FactoryBean` should use CTOR injection if there is a potential hierarchical dependency.

NOTE: there is no tests on the matter, since we don't change the components behavior.
The `JPA` sample application will be changed to the Boot to track this fix.

**Cherry-pick to 4.2.x**

Address PR comments and fix other `FactoryBean`s for the same issue, when it is reasonable

Polishing

Address PR comments

Make setter `setSockJsTaskScheduler` as `public`

spring-integration-zookeeper/src/test/java/org/springframework/integration/zookeeper/config/LeaderInitiatorFactoryBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 the original author or authors.
+ * Copyright 2015-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,6 +44,7 @@ import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
 /**
  * @author Gary Russell
+ * @author Artem Bilan
  * @since 4.2
  *
  */
@@ -85,7 +86,10 @@ public class LeaderInitiatorFactoryBeanTests extends ZookeeperTestSupport {
 
 		@Bean
 		public LeaderInitiatorFactoryBean leaderInitiator(CuratorFramework client) {
-			return new LeaderInitiatorFactoryBean(client, "/siTest/", "foo");
+			return new LeaderInitiatorFactoryBean()
+					.setClient(client)
+					.setPath("/siTest/")
+					.setRole("foo");
 		}
 
 		@Bean