Fix JdbcLockRegDiffClientTests race condition

https://build.spring.io/browse/INT-MJATS41-1242

When different `DefaultLockRepository` instances use the same client id,
there is a possibility that they will update the same row in the table.
This way we have a chance that not only one obtains a lock and try to
add a value to the collection.

* Remove the test-case for the same client id as non-stable and even
dangerous by the the distributed lock purpose
* Use `tryLock(Long.MAX_VALUE)` to really ensure the wait behavior
during the concurrent loop
* Use `20` for thread pool to align with the tasks amount

**Cherry-picked to 4.3.x**

Author: artembilan

spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/lock/JdbcLockRegistryDifferentClientTests.java

@@ -191,26 +191,19 @@ public void testBothLock() throws Exception {
 
 	@Test
 	public void testOnlyOneLock() throws Exception {
-		testOnlyOneLock(null);
-		testOnlyOneLock("AABBCCDD");
-	}
-
-	private void testOnlyOneLock(String id) throws Exception {
 		for (int i = 0; i < 100; i++) {
 			final BlockingQueue<String> locked = new LinkedBlockingQueue<>();
 			final CountDownLatch latch = new CountDownLatch(20);
-			ExecutorService pool = Executors.newFixedThreadPool(6);
-			ArrayList<Callable<Boolean>> tasks = new ArrayList<Callable<Boolean>>();
-			final DefaultLockRepository client = (id == null) ?
-					new DefaultLockRepository(this.dataSource) :
-					new DefaultLockRepository(this.dataSource, id);
-			client.afterPropertiesSet();
-			this.context.getAutowireCapableBeanFactory().autowireBean(client);
+			ExecutorService pool = Executors.newFixedThreadPool(20);
+			ArrayList<Callable<Boolean>> tasks = new ArrayList<>();
+
 			for (int j = 0; j < 20; j++) {
 				Callable<Boolean> task = () -> {
+					DefaultLockRepository client = new DefaultLockRepository(this.dataSource);
+					client.afterPropertiesSet();
 					Lock lock = new JdbcLockRegistry(client).obtain("foo");
 					try {
-						if (locked.isEmpty() && lock.tryLock()) {
+						if (locked.isEmpty() && lock.tryLock(Long.MAX_VALUE, TimeUnit.MILLISECONDS)) {
 							if (locked.isEmpty()) {
 								locked.add("done");
 								return true;