partial fix for #19197 - get barline length right

1.3 scores with staves of fewer or more than 5 lines are imported with incorrect barline liengths.  This fixes that.  So 1-line percussion staves should import well.

3-line drum sets are another matter.  In 1.3, these had a staff spacing of 2sp.  I have identified the place where we could potentially preserve this and I have implemented the change.  But it is commented out here, as it doesn't actually produce the correct results since the drum notes (and rest) would need to be moved to two lines down in order for this to produce similar layout as 1.3.