fix import order

Author: iaorekhov-1980

fe/fe-core/src/test/java/org/apache/doris/mysql/authenticate/ldap/LdapAuthenticatorTest.java

@@ -29,8 +29,8 @@
 import mockit.Expectations;
 import mockit.Mocked;
 import org.junit.After;
-import org.junit.Before;
 import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 
 import java.io.IOException;