Breaking: #75834 - Reorder processing of TCA Select items

See forge#75834

Description

It's now possible again to add and remove items via pageTSconfig after itemsProcFunc has been processed for TCA select fields.

Impact

Items generated by itemsProcFunc no longer have the highest priority.

Affected Installations

Any installation that relied on itemsProcFunc being the source of truth for a given field.

Migration

Cross check if you added or removed items via pageTSconfig. These might be really gone now.