fix legend

[maraab23]

ggplot2 release 3.5.0 breaks legends: key glyph for non-visited states don't show up anymore

• Smarter keys (attempt 2) tidyverse/ggplot2#5502
• legend key does not respect scale_fill_manual(..., drop = FALSE) tidyverse/ggplot2#5586

Fix: add show.legend = T to the geom*-calls