[FIX] payment_mercado_pago: fix checkout process

[ALopez-Adhoc]

Description of the issue/feature this PR addresses:
'sandbox_init_point' is deprecated. Although it still exists in the payment preference creation, it is no longer functional in the result; 'init_point' should always be used instead. In the case of test credentials, 'init_point' will always behave as if in a test environment.

Steps to Reproduce:

• Install the payment_mercado_pago module.
• Configure the account with the following mercado_pago_access_token: TEST-4811719641145832-020115-c5caffc149634e3e9d72fde2b74544d8__LD_LA__-172837665
• Initiate a payment process with a published mercado_pago payment provider link.
  The following error occurs:

Removing the 'sandbox' word from the URL generates the payment process correctly.

Current behavior before PR:
Payment cannot be made in sandbox mode using payment credentials with the mercado_pago provider.

Desired behavior after PR is merged:
The payment process should be completed successfully using test credentials for the mercado_pago provider.

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[robodoo]

Pull request status dashboard.

[lathama]

@ALopez-Adhoc I think the git commit msg needs a space after [FIX] but I don't see it mentioned at https://www.odoo.com/documentation/17.0/contributing/development/git_guidelines.html#tag-and-module-name but also possible it does not like the :

[ALopez-Adhoc]

@lathama Hi Andrew! Thank you for the feedback. I reviewed the documentation and made the corresponding changes. I did not remove the ':' since it appeared after the module name, but I added spaces after the tag and the ':'.

[lathama]

Awesome sauce! I was sleepy when commenting, the : was a mistake on my part.

[lathama]

@vava-odoo can you connect a code owner to review this?

[vava-odoo]

@lathama Unlike issues, PRs are automatically assiged to the responsible team. In this case, the one about online payments was pinged and will answer as soon as they can.

[AntoineVDV]

Hi @ALopez-Adhoc, do you have a link to a statement from MercadoPago about deprecating the sandbox_init_point key?

I've tested the payment page while keeping the sandbox. subdomain with your API key and it worked fine. The official documentation of the Checkout API also doesn't mention deprecating that response key.