Display bracket with only one staff in a system

If there is only one staff in a ChoirStaff or StaffGroup context, the bracket and the starting bar line will not be displayed by default. This can be changed by setting the collapse-height property to a value less than the number of staff lines in the staff.

Note that in contexts such as PianoStaff and GrandStaff where the systems begin with a brace instead of a bracket, another property has to be set, as shown on the second system in the example.

\version "2.24"

\score {
  \new StaffGroup <<
    % Must be lower than the actual number of staff lines
    \override StaffGroup.SystemStartBracket.collapse-height = 4
    \override Score.SystemStartBar.collapse-height = 4
    \new Staff {
      c'1
    }
  >>
}
\score {
  \new PianoStaff <<
    \override PianoStaff.SystemStartBrace.collapse-height = 4
    \override Score.SystemStartBar.collapse-height = 4
    \new Staff {
      c'1
    }
  >>
}