correct barline on oneline to hidden staff

[sammik]

Resolves #26675

1. commit: missing bottom half of single line staff barline

2. commit: barlines overlapping, and cleanup - now span thru barlines always starts at top line, and ends at next staff top line
   

also it is now possible to customise bottom of barline at singe line staff

vtests are, I think good

not sure just about one. I think it is good now, but may be I miss something
before:

after:

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• The title of the PR describes the problem it addresses
• Each commit's message describes its purpose and effects, and references the issue it resolves
• If changes are extensive, there is a sequence of easily reviewable commits
• The code in the PR follows the coding rules
• There are no unnecessary changes
• The code compiles and runs on my machine, preferably after each commit individually
• I created a unit test or vtest to verify the changes I made (if applicable)