Followup GH-19022

[arnaud-lb]

This fixes some oversights from GH-19022:

• Use the newly introduced zend_call_trampoline_arginfo in zend_get_call_trampoline_func().
• Update the arg name to arguments instead of args, to match the documentation: https://www.php.net/__call#language.oop5.overloading.methods
• Use the original arg_info when creating an FCC of a trampoline to reduce duplication

None of these changes are observable, but this is cleaner, and this becomes observable in GH-20848.