Try to make if_transform_strings perf test faster (#12598)

tests/performance/if_transform_strings_to_enum.xml

 <test>
     <preconditions>
-        <table_exists>hits_10m_single</table_exists>
         <table_exists>hits_100m_single</table_exists>
     </preconditions>
 
     <query>SELECT length(URL) > 1000 ? 'LONG' : 'SHORT' as x FROM hits_100m_single GROUP BY x FORMAT Null</query>
-    <query>SELECT transform(number, [2, 4, 6], ['google', 'yandex', 'yahoo'], 'other') as x FROM numbers(1000000000) GROUP BY x FORMAT Null</query>
+    <query>SELECT transform(number, [2, 4, 6], ['google', 'yandex', 'yahoo'], 'other') as x FROM numbers(100000000) GROUP BY x FORMAT Null</query>
+    
+    <query>SELECT length(URL) > 1000 ? 'LONG' : 'SHORT' as x FROM hits_100m_single GROUP BY x FORMAT Null SETTINGS optimize_if_transform_strings_to_enum = 1</query>
+    <query>SELECT transform(number, [2, 4, 6], ['google', 'yandex', 'yahoo'], 'other') as x FROM numbers(100000000) GROUP BY x FORMAT Null SETTINGS optimize_if_transform_strings_to_enum = 1</query>
 </test>