miyao cannot find complete staves on Einsiedeln 269v

This issue comes from fixing #1124 and is originally documented in the comment [here](https://github.com/DDMAL/Rodan/issues/1124#issuecomment-1948744904).
Here's the dilated output for 269v from Rodan workflow in #1124 .

Here's the output from the original Gamera miyao.

With blackness > 0.5, miyao cannot spot any staff and return an empty list. If we keep lowering blackness, we will get sporadic pattern, still not the full page of staves, as such (0.45):

And if we run the Rodan workflow again the result becomes this (slightly better but not good enough):

My speculation is that the extra bottom line distracts miyao from telling staves from the background.
Ich says this is a problem with miyao. Would it be a problem with the gamera wrapper [miyao.py](rodan-main/code/rodan/jobs/gamera_rodan/wrappers/toolkits/music_staves/miyao.py) in rodan?