Remove unused field

Signed-off-by: Asim Mahmood <asim.seng@gmail.com>

Author: asimmahmood1

server/src/test/java/org/opensearch/search/aggregations/bucket/histogram/AutoDateHistogramAggregatorTests.java

@@ -1049,7 +1049,6 @@ private void indexSampleData(List<ZonedDateTime> dataset, RandomIndexWriter inde
             document.add(new LongPoint(DATE_FIELD, instant));
             document.add(new LongPoint(INSTANT_FIELD, instant));
             document.add(new SortedNumericDocValuesField(NUMERIC_FIELD, i));
-            document.add(new StringField("filterField", "a", Field.Store.NO));
             indexWriter.addDocument(document);
             document.clear();
             i += 1;