Issue 4519: event-chord-wrap! needs to call expand-repeat-notes!

Issue 4519: event-chord-wrap! needs to call expand-repeat-notes!

The action of event-chord-wrap! will make it impossible to figure out
repeat notes (notes without pitch but with duration) but one must not
expand repeat notes before expanding chord repeats, and
event-chord-wrap! does expand chord repeats.  So it needs to call
expand-repeat-chords! as well before doing its compatibility processing.