Fix a calculation in TidStoreCreate().
Since we expect that the max_bytes is in bytes, not in kilobytes, it
should not be multiplied by 1024.
Introduced by
30e144287a.
Reported-by: John Naylor, David Rowley
Reviewed-by: John Naylor
Discussion: https://postgr.es/m/CANWCAZZTE-14ofsucofTuhFsfuDGBNf%3DNZb22TMYT8bxA41oQQ%40mail.gmail.com
Discussion: https://postgr.es/m/CAApHDvojg82NDaDEpj1WEZSbVTafj%3DDRmW%2BFrkBdW8ScL4OFxA%40mail.gmail.com