Use MinorUnitsConverterInterface::toMinorUnits, remove custom service

vmarchuk → made their first commit to this issue’s fork.

Since PaymentGatewayInterface::toMinorUnits is already deprecated we need to replace the custom service "commerce_affirm.minor_units" with "commerce_price.minor_units_converter".

Opened MR with fixes.

Committing with a quick follow-up.

Automatically closed - issue fixed for 2 weeks with no activity.