Fix StressTests Java BigQueryIO job flakiness (#32803)

* Fix assert for at least once method

* Refactoring

it/google-cloud-platform/src/test/java/org/apache/beam/it/gcp/bigquery/BigQueryIOST.java

@@ -84,6 +84,7 @@ public final class BigQueryIOST extends IOStressTestBase {
  private static final String READ_ELEMENT_METRIC_NAME = "read_count";
  private static final String STORAGE_WRITE_API_METHOD = "STORAGE_WRITE_API";
  private static final String STORAGE_API_AT_LEAST_ONCE_METHOD = "STORAGE_API_AT_LEAST_ONCE";
+ private static final double STORAGE_API_AT_LEAST_ONCE_MAX_ALLOWED_DIFFERENCE_FRACTION = 0.00001;
 
  private static BigQueryResourceManager resourceManager;
  private static String tableName;
@@ -334,11 +335,14 @@ private void generateDataAndWrite(BigQueryIO.Write<byte[]> writeIO) throws IOExc
 
  // Depending on writing method there might be duplicates on different sides (read or write).
  if (configuration.writeMethod.equals(STORAGE_API_AT_LEAST_ONCE_METHOD)) {
+ long allowedDifference =
+ (long) (numRecords * STORAGE_API_AT_LEAST_ONCE_MAX_ALLOWED_DIFFERENCE_FRACTION);
+ long actualDifference = (long) numRecords - rowCount;
  assertTrue(
  String.format(
- "Number of rows in the table (%d) is less than the expected number (%d). Missing records: %d",
- rowCount, (long) numRecords, (long) numRecords - rowCount),
- rowCount >= numRecords);
+ "Row difference (%d) exceeds the limit of %d. Rows: %d, Expected: %d",
+ actualDifference, allowedDifference, rowCount, (long) numRecords),
+ actualDifference <= allowedDifference);
  } else {
  assertTrue(
  String.format(