[checkout][normalizer] Add comment about why set public_api_key first.
[checkout][normalizer] Add comment about why set public_api_key first.

If public_api_key is set in most cases we can track the source of the problem from our logs and to be able of communicate the merchant about any issue

aplazame/aplazame-js,aplazame/aplazame-js,aplazame/aplazame-js