Refactor QueryBuilderResolver Rewrite Logic (#119740) (#119834)

* Refactor QueryBuilderResolver Rewrite Logic

This commit improves the rewrite logic by switching to reference comparison for termination checks.
While the existing implementation functions correctly, the rewrite contract is designed to compare references rather than performing a full object comparison, which is unnecessary.

Additionally, this change guarantees that only a single rewrite pass is executed per query builder.

* avoid getting the value

---------

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Co-authored-by: Felix Barnsteiner <felixbarny@users.noreply.github.com>

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/QueryBuilderResolver.java

@@ -150,15 +150,12 @@ public FullTextFunctionsRewritable rewrite(QueryRewriteContext ctx) throws IOExc
             Map<FullTextFunction, QueryBuilder> results = new HashMap<>();
 
             boolean hasChanged = false;
-            for (FullTextFunction func : queryBuilderMap.keySet()) {
-                var initial = queryBuilderMap.get(func);
-                var rewritten = Rewriteable.rewrite(initial, ctx, false);
+            for (var entry : queryBuilderMap.entrySet()) {
+                var initial = entry.getValue();
+                var rewritten = initial.rewrite(ctx);
+                hasChanged |= rewritten != initial;
 
-                if (rewritten.equals(initial) == false) {
-                    hasChanged = true;
-                }
-
-                results.put(func, rewritten);
+                results.put(entry.getKey(), rewritten);
             }
 
             return hasChanged ? new FullTextFunctionsRewritable(results) : this;