fix: do not use any random staleness for partitioned queries

Author: olavloite

google-cloud-spanner/src/test/java/com/google/cloud/spanner/it/ITBatchReadTest.java

@@ -341,7 +341,6 @@ public void testRunPartitionedQuery() {
     try (Connection connection = options.getConnection()) {
       // Use dynamic parallelism.
       connection.setMaxPartitionedParallelism(0);
-      connection.setReadOnlyStaleness(getRandomBound());
 
       BitSet seenRows = new BitSet(numRows);
       try (PartitionedQueryResultSet resultSet =