Realex: update avs/address code creation

[slogsdon]

[bpollack]

Thanks for the PR. If this is still relevant to you (sorry it's been awhile!), I'd appreciate at least some information about what this is correcting/fixing and why, and ideally also an equivalent note in the remote tests so we can verify that it works properly.

[slogsdon]

@bpollack Thanks for following up.

This change corrects AVS behavior for non-GB countries that support AVS through the Realex gateway. Here's the relevant Realex documentation that covers this functionality: https://developer.realexpayments.com/#!/api/fraud-management/avs. Essentially, only GB address should strip non-numeric characters from the postal code and first address line when constructing the code field that is sent to the gateway. Previously, it would incorrectly perform this for all cases.

Are you able to confirm if you're looking to add tests/assertions for this change to match the unit test assertions?