Fix Checkstyle violation

https://build.spring.io/browse/INT-SI43X-239/

Author: artembilan

spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/leader/JdbcLockRegistryLeaderInitiatorTests.java

@@ -25,7 +25,6 @@
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
-import org.apache.log4j.Level;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;