Always set start- and end-tick at measure boundaries for Volta

[mike-spa]

Resolves: #24189

As far as I can tell, there has never been any check to force Voltas to have their start- and end-tick at the measure boundaries. It's just that the start- and end-tick used to be ignored when calculating the graphical end points of the line, and the line would just be drawn to fit the measure. That's obviously not great, cause it means that what you see doesn't match the underlying data, and most importantly that the underlying data is incorrect.

This PR introduces a simple check that ensures Voltas have the correct start and end tick. The side-issue reported in the comment is also fixed.