follow up on rand(const) usage in regression test

In mysql/queries/working_tpch1/qa_fe_cnxFunctions/RAND.sql,

there are queries like
select rand(1), rand(2) from t1;

We need to verify that rand(const) makes it to columnstore. Since it doesn't reference anything in a storage engine, the server may be doing that calculation.

If time is short, skip answering the question and change the const parameters to column names.