Fixed ServerLowLevel tests not running

JUnit only runs tests in classes that have a name that ends in Test,
the class in question had a name that ended in Tests, with an added s.
As a result, the tests in this class were never executed. This renames
the class to not have the added s.

broker/src/test/java/io/moquette/integration/ServerLowlevelMessagesIntegrationTests.java → broker/src/test/java/io/moquette/integration/ServerLowlevelMessagesIntegrationTest.java

@@ -40,9 +40,9 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.junit.jupiter.api.Assertions.*;
 
-public class ServerLowlevelMessagesIntegrationTests {
+public class ServerLowlevelMessagesIntegrationTest {
 
-    private static final Logger LOG = LoggerFactory.getLogger(ServerLowlevelMessagesIntegrationTests.class);
+    private static final Logger LOG = LoggerFactory.getLogger(ServerLowlevelMessagesIntegrationTest.class);
     static MqttClientPersistence s_dataStore;
     Server m_server;
     Client m_client;