cubicweb #9135780 sqlgenobjectstore chokes on Binary data [validation pending]

It used to fall back from COPY to executemany.

prioritynormal
typebug
done in3.20.12
load0.250
load left0.000
closed by#de59a60a9e40 [dataimport] Fallback from COPY to executemany (closes #9135780)
patch[dataimport] Fallback from COPY to executemany [applied]