Refactor: remove stale comments

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

datasources/src/main/java/org/opensearch/sql/datasources/service/DataSourceServiceImpl.java

@@ -10,7 +10,6 @@
 
 import java.util.*;
 import java.util.stream.Collectors;
-
 import org.opensearch.sql.datasource.DataSourceService;
 import org.opensearch.sql.datasource.RequestContext;
 import org.opensearch.sql.datasource.model.DataSource;

integ-test/src/test/java/org/opensearch/sql/calcite/standalone/CalcitePPLIntegTestCase.java

@@ -374,7 +374,6 @@ public QueryPlanFactory queryPlanFactory(ExecutionEngine executionEngine) {
           new Analyzer(
               new ExpressionAnalyzer(functionRepository), dataSourceService, functionRepository);
       Planner planner = new Planner(LogicalPlanOptimizer.create());
-      // NodeClient is not used in integration test, so we pass null
       QueryService queryService =
           new QueryService(analyzer, executionEngine, planner, dataSourceService, settings);
       return new QueryPlanFactory(queryService);

ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLAbstractTest.java

@@ -73,7 +73,6 @@ protected CalcitePlanContext createBuilderContext() {
   /** Creates a CalcitePlanContext with transformed config. */
   private CalcitePlanContext createBuilderContext(UnaryOperator<RelBuilder.Config> transform) {
     config.context(Contexts.of(transform.apply(RelBuilder.Config.DEFAULT)));
-    // NodeClient is not used in this test, so we pass null
     return CalcitePlanContext.create(config.build(), PPL);
   }