Use SORT to push down the EVAL clause, so it's executed on local nodes

Author: carlosdelest

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

@@ -31,6 +31,7 @@ public void testExtractSnippets() {
         var query = """
             FROM test
             | EVAL x = extract_snippets(content, "fox", 1, 10)
+            | SORT x
             | KEEP x
             """;