META-334: Fix duplicate bold checkout orders

[zliu7878]

Issue:

• The bold_checkout_order is currently saved twice in the db, first in the CheckoutSubmitAllAfterObserver, and then again the at the place order endpoint

Fix:

• Add a check at the place order endpoint and only save to the bold_checkout_order if the mangeto order with the bold public id does not exist in the db

[mwraich]

Tested 6 orders, 3 on V1 and 3 on V1 (counting id 60 and up) and it all looks good.

Made this ticket as a tech-debt clean up to eliminate the duplication.