Fix SearchQueryIT to not depend on percentage (opensearch-project#11233…

…) (opensearch-project#11243)

The CommonTermsQuery tests in SearchQueryIT had one case that depended
on the default cutoff frequency percentage. A recent change for
concurrent search increased the number of deleted documents that could
be indexed in the "indexRandom" helper method, and it turns out the
cutoff percentage is calculated from a max docs value that includes
deleted docs. This change replaces the default percentage with an absolute
value (number of documents that must match) so it is no longer
susceptible to behavior change due to number of deleted documents.


(cherry picked from commit 3509500)

Signed-off-by: Andrew Ross <[email protected]>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

server/src/internalClusterTest/java/org/opensearch/search/query/SearchQueryIT.java

@@ -394,7 +394,19 @@ public void testCommonTermsQuery() throws Exception {
         assertSecondHit(searchResponse, hasId("2"));
         assertThirdHit(searchResponse, hasId("3"));
 
-        searchResponse = client().prepareSearch().setQuery(commonTermsQuery("field1", "the huge fox").lowFreqMinimumShouldMatch("2")).get();
+        // cutoff frequency of 1 makes all terms high frequency so the query gets rewritten as a
+        // conjunction of all terms (the lowFreqMinimumShouldMatch parameter is effectively ignored)
+        searchResponse = client().prepareSearch()
+            .setQuery(commonTermsQuery("field1", "the huge fox").cutoffFrequency(1).lowFreqMinimumShouldMatch("2"))
+            .get();
+        assertHitCount(searchResponse, 1L);
+        assertFirstHit(searchResponse, hasId("2"));
+
+        // cutoff frequency of 100 makes all terms low frequency, so lowFreqMinimumShouldMatch=3
+        // means all terms must match
+        searchResponse = client().prepareSearch()
+            .setQuery(commonTermsQuery("field1", "the huge fox").cutoffFrequency(100).lowFreqMinimumShouldMatch("3"))
+            .get();
         assertHitCount(searchResponse, 1L);
         assertFirstHit(searchResponse, hasId("2"));