Fix RRF tests

Author: ioanatia

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/operator/RrfScoreEvalOperator.java

@@ -68,8 +68,11 @@ protected Page process(Page page) {
         for (int i = 0; i < page.getBlockCount() - 1; i++) {
             projections[i] = i == scorePosition ? page.getBlockCount() - 1 : i;
         }
-
-        return page.projectBlocks(projections);
+        try {
+            return page.projectBlocks(projections);
+        } finally {
+            page.releaseBlocks();
+        }
     }
 
     @Override

x-pack/plugin/esql/qa/testFixtures/src/main/resources/rrf.csv-spec

@@ -120,6 +120,7 @@ FROM semantic_text METADATA _id, _score, _index
        ( WHERE semantic_text_field:"something else" | SORT _score DESC | LIMIT 2)
 | RRF
 | EVAL _score = round(_score, 4)
+| EVAL _fork = mv_sort(_fork)
 | KEEP _fork, _score, _id, semantic_text_field
 ;
 

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/RrfIT.java

@@ -40,6 +40,7 @@ public void testRrf() {
                ( WHERE content:"fox" | SORT _score, _id DESC )
                ( WHERE content:"dog" | SORT _score, _id DESC )
             | RRF
+            | EVAL _fork = mv_sort(_fork)
             | EVAL _score = round(_score, 4)
             | KEEP id, content, _score, _fork
             """;