Fix flaky unit tests in Rds source

data-prepper-plugins/rds-source/src/test/java/org/opensearch/dataprepper/plugins/source/rds/export/DataFileSchedulerTest.java

@@ -187,12 +187,13 @@ void test_data_file_loader_throws_exception_then_give_up_partition() {
     }
 
     @Test
-    void test_shutdown() {
+    void test_shutdown() throws InterruptedException {
         DataFileScheduler objectUnderTest = createObjectUnderTest();
         final ExecutorService executorService = Executors.newSingleThreadExecutor();
         executorService.submit(objectUnderTest);
 
         objectUnderTest.shutdown();
+        Thread.sleep(100);
 
         verifyNoMoreInteractions(sourceCoordinator);
         executorService.shutdownNow();

data-prepper-plugins/rds-source/src/test/java/org/opensearch/dataprepper/plugins/source/rds/export/ExportSchedulerTest.java

@@ -262,12 +262,13 @@ void test_given_export_partition_and_null_export_task_id_then_close_partition_wi
     }
 
     @Test
-    void test_shutDown() {
+    void test_shutDown() throws InterruptedException {
         lenient().when(sourceCoordinator.acquireAvailablePartition(ExportPartition.PARTITION_TYPE)).thenReturn(Optional.empty());
 
         final ExecutorService executorService = Executors.newSingleThreadExecutor();
         executorService.submit(exportScheduler);
         exportScheduler.shutdown();
+        Thread.sleep(100);
         verifyNoMoreInteractions(sourceCoordinator, snapshotManager, exportTaskManager, s3Client,
                 exportJobSuccessCounter, exportJobFailureCounter, exportS3ObjectsTotalCounter);
         executorService.shutdownNow();