Closes #701 Ensure the exception type is the same as 2.3.x

src/main/java/com/zaxxer/hikari/HikariConfig.java

@@ -769,7 +769,7 @@ public class HikariConfig implements HikariConfigMXBean
             LOGGER.error("{} - cannot use driverClassName and dataSourceClassName together.", poolName);
             // NOTE: This exception text is referenced by a Spring Boot FailureAnalyzer, it should not be
             // changed without first notifying the Spring Boot developers.
-            throw new IllegalArgumentException("cannot use driverClassName and dataSourceClassName together.");
+            throw new IllegalStateException("cannot use driverClassName and dataSourceClassName together.");
          }
          else if (jdbcUrl != null) {
             LOGGER.warn("{} - using dataSourceClassName and ignoring jdbcUrl.", poolName);