cubicweb #2405487 dev instance should not serve /data files [validation pending]

/data/image.png doesn't work anymore (from css) in cubicweb 3.15 ... but still works in dev mode. This can be misleading.

prioritynormal
typebug
done in3.15.2
load0.200
load left0.000
closed by#65fecbeb9c3a [webconfig] debug mode should not be special wrt data_url handling (closes #2405487)