The new namespace is supported from WooCommerce 6.4.0 so we don't need
to support the old namespace any more.
Some users reported issues with BC class aliases provided by Woo.
[MAILPOET-4774]
The current implementaiton of the deprecation of woocommerce_blocks_checkout_update_order_from_request
has a bug which causes a fatal error of our plugin. We do not want immediately switch to the
latest hook in order to keep older versions of the plugin compatible with MailPoet.
Therefore we switch to the deprecated __experimental ancestor for now.
[MAILPOET-4206]
