cubicweb #3705791 [ucsvreader] don't always skip the first line when ignore_errors is True [validation pending]

ucsvreader always skips the first line out of the csv.reader if ignore_errors is enabled, regardless of skipfirst.

prioritynormal
typebug
done in3.18.5
load0.100
load left0.000
closed by#aa982b7c3f2a [dataimport] Prevent ucsvreader from skipping the first line when ignore_errors is True (closes #3705791)
patch[dataimport] Prevent ucsvreader from skipping the first line when ignore_errors is True (closes #3705791) [applied]