Bulk upload proofs are not available for validation because the ready_for_price_tag_validation parameter is false by default

[teolemon]

Bulk upload proofs are not available for validation because the ready_for_price_tag_validation parameter is false by default for proofs sent by the app, preventing them from appearing on the PVA.

Fix: Change the default behavior so that proofs sent by the app have ready_for_price_tag_validation set to true, making them available for validation on the PVA.

[teolemon]

Cc @raphodn

[monsieurtanuki]

@teolemon I've just created openfoodfacts/openfoodfacts-dart#1066, so that we can set the ready_for_price_tag_validation when uploading a proof from Smoothie.
Next question: should we consider as "ready_for_price_tag_validation:true" all bulk proof uploads in Smoothie? All price tag uploads in Smoothie?