Fix #20615:

In the New Score wizard and in the Instruments dlg box, the "Staff Type" combo is lost when staves or parts are moved up or down.
Merge pull request #287 from mgavioli/Fix_#20615_Instr_dlg_staff_type_combo_lost_on_moving_staves

Fix #20615: Instr. dlg box: Staff Type combo lost on moving staves