Remove more uses of CRM_Core_DAO::$_nullArray that are unncessary

[seamuslee001]

Overview

Title says it all

ping @eileenmcnaughton

[civibot]

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[eileenmcnaughton]

I looked through these to check the removed param really was optional. The regex function was the only one that didn't fit a pretty narrow pattern but that was only called from one place & neither the calling function nor the function defined it as returning by regex - so looks good to me