fix: TAP-6786 validate doris be nodes when testing connection write privilege

Author: mnianqi

connectors/doris-connector/src/main/java/io/tapdata/connector/doris/DorisTest.java

@@ -20,7 +20,6 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 
 import static io.tapdata.base.ConnectorBase.testItem;