Only presets that still name their parent as 2.4.2 did and have no printer
list of their own are offered, and a preset changed after it was found is
left alone. The startup prompt appears once, after upgrading from 2.4.2 or
earlier, as a standard dialog that keeps "Don't remind me again"; Help >
Migrate Filament Presets is unchanged. Migrating no longer overwrites an
unsaved printer-list edit or marks the project modified.