REF - Swap CRM_Utils_Array::collect with vanilla array_column

REF - Swap CRM_Utils_Array::collect with vanilla array_column

The only difference between these functions (when only passed 2 params)
is the order of the params, and the fact that array_column does not preserve keys.
So CRM_Utils_Array::collect can be swapped out 1-1 with array_column anywhere
that the keys don't matter to the return value.