Chore: Remove unneeded code related to `prepend` option

[RyanCavanaugh]

Assuming #52312 stays in through 5.0, there's a decent amount of code we can remove from the emitter, specifically stuff introduced by #22420

[DanielRosenwasser]

Does this assume removal of prepend, or just deprecation (as in #52312)?

[RyanCavanaugh]

This work item is "Once we remove support for the option entirely, then delete all the code for it"

[sheetalkamat]

Completed in #57472