Removed obsolete module Mage_Centinel

[fballiano]

This PR targets next

Mage_Centinel is a module that provided 3DS for payment methods in OpenMage. We're talking about 3DS 1.0, not 3DS 2.0 which is more or less mandatory for all credit card providers all over the world nowadays.

I've conducted quite a few tests and I'm pretty sure the module is not working anymore, when you enable it you will have this error message:

The XmlParser class is a reserved name in php8:

Also if you remove that class from the filesystem you will see:

So:

• 3DS 1.0 is obsolete and nobody should use it anymore, continuing to use the outdated Centinel module would expose merchants to potential security risks and compatibility issues with modern payment systems and regulations.
• the name "Centinel" doesn't really exist since 2011, when CardinalCommerce was acquired by Visa and the Centinel service became part of Visa's product offerings under the name "Visa Secure"
• the Centinel module is actually broken and doesn't technically work anymore

I think it's safe to remove this code from OpenMage v21.

Closes #3755

[kiatng]

This and following functions don't seem to have anything to do with Centinel. Is it ok to delete?

[fballiano]

true, I didn't remove them at first but phpstan started complaining, you can see it here:
https://github.com/OpenMage/magento-lts/actions/runs/8931953986/job/24534948827

because those methods are private and not used so they should be un-usable by anybody

I think

[kiatng]

Also need to cleanup here

[fballiano]

@kiatng done! thanks for noticing!

[luigifab]

Buy buy Centinel! Disabled for me.

[kiatng]

See https://docs.adyen.com/online-payments/3d-secure-for-regulation-compliance/

3-D Secure 1 and related technology are no longer supported by all major cards.