Remove column count validation

That doesn't really tell us much in this test, anyway.

Author: alex-spies

x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/RestEsqlTestCase.java

@@ -1024,7 +1024,6 @@ public void testMultipleBatchesWithLookupJoin() throws IOException {
             );
             Map<String, Object> result = runEsql(query);
             var columns = as(result.get("columns"), List.class);
-            assertEquals(22, columns.size());
             var values = as(result.get("values"), List.class);
             assertEquals(10, values.size());
         }