[lazerg]

Since the upload progress handler started decoding the session with every object kept as __PHP_Incomplete_Class, it refuses records that have a property named __PHP_Incomplete_Class_Name, __PHP_Incomplete_Class_Serialized or __PHP_Incomplete_Enum_Case. That refusal went through the normal decode failure path, which destroys the session, even though a regular session_start() reads the same record without a problem.

When the decode fails inside the upload progress handler, the session is now only closed and the progress update is skipped, so the stored record stays as it was and the request deals with it when it starts the session itself. I updated the expectations of rfc1867_incomplete_class_reserved_props.phpt to match.

Fixes GH-24493