Fixing the address checkbox being unchecked on payment step.

[eduard13]

Description

When an offline custom payment method is used, the 'My billing and shipping address are the same' checkbox from payment step is unchecked, if the shipping address is updated.

Please check the issue's description for more details.

Fixed Issues (if relevant)

1. Custom Payment Method doesn't uncheck 'My billing and shipping address are the same' #14819: Custom Payment Method doesn't uncheck 'My billing and shipping address are the same'

Manual testing scenarios

1. Create an offline payment method
2. Add a product to cart
3. Go to Checkout
4. Fill in the shipping address
5. Go to Payment Step
6. We have our new payment method, and one more - Checkmo
7. Select Checkmo
8. Under Selected Payment Method - My billing and shipping address are the same is checked and below we have the billing address = shipping address
   
9. Go back to shipping step and change some fields
10. Come back on the Payment Step

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @eduard13. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento-engcom-team give me test instance - deploy test instance based on PR changes
• @magento-engcom-team give me {$VERSION} instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Assistant documentation

[magento-engcom-team]

Hi @eduard13. Thank you for your contribution.
We will aim to release these changes as part of 2.2.7.
Please check the release notes for final confirmation.

Please, consider to port this solution to 2.3 release line.
You may use Porting tool to port commits automatically.