Add try catch into cron process when new adyen_order_payment entity is added

Turned out that other plugins can intercept into invoice creation and
these are potential sources of exceptions. After inserting a new
adyen_order_payment entity we start the invoice creation process and if
something goes wrong during that process we reprocess the notification in
the next batch. Therefore the adyen_order_payment is already saved and the
next run will violate the unique constraint setting of the table.

This is a quick solution to prevent the process to stop and the order to
get stuck because of this exception.

Resolves GitHub issues: #603, #610