Fix test testMultiKnnClauses (#93047)

The test uses random vectors, consequently it is possible that vector_1 values are much closer than vector_2 values. Increasing boost to ensure order.

Author: benwtrent

server/src/test/java/org/elasticsearch/action/search/KnnSearchSingleNodeTests.java

@@ -186,13 +186,13 @@ public void testMultiKnnClauses() throws IOException {
         createIndex("index", indexSettings, builder);
 
         for (int doc = 0; doc < 10; doc++) {
-            client().prepareIndex("index").setSource("vector", randomVector(), "text", "hello world", "number", 1).get();
-            client().prepareIndex("index").setSource("vector_2", randomVector(), "text", "hello world", "number", 2).get();
+            client().prepareIndex("index").setSource("vector", randomVector(1.0f, 2.0f), "text", "hello world", "number", 1).get();
+            client().prepareIndex("index").setSource("vector_2", randomVector(20f, 21f), "text", "hello world", "number", 2).get();
             client().prepareIndex("index").setSource("text", "goodnight world", "number", 3).get();
         }
         client().admin().indices().prepareRefresh("index").get();
 
-        float[] queryVector = randomVector();
+        float[] queryVector = randomVector(20f, 21f);
         KnnSearchBuilder knnSearch = new KnnSearchBuilder("vector", queryVector, 5, 50).boost(5.0f);
         KnnSearchBuilder knnSearch2 = new KnnSearchBuilder("vector_2", queryVector, 5, 50).boost(10.0f);
         SearchResponse response = client().prepareSearch("index")
@@ -213,7 +213,7 @@ public void testMultiKnnClauses() throws IOException {
         assertThat(agg.getAvg(), equalTo(2.25));
         assertThat(agg.getSum(), equalTo(45.0));
 
-        // Because of the boost, vector_2 results should appear first
+        // Because of the boost & vector distributions, vector_2 results should appear first
         assertNotNull(response.getHits().getAt(0).field("vector_2"));
     }
 
@@ -372,4 +372,12 @@ private float[] randomVector() {
         }
         return vector;
     }
+
+    private float[] randomVector(float dimLower, float dimUpper) {
+        float[] vector = new float[VECTOR_DIMENSION];
+        for (int i = 0; i < vector.length; i++) {
+            vector[i] = (float) randomDoubleBetween(dimLower, dimUpper, true);
+        }
+        return vector;
+    }
 }