Add BCSS to leaderboard

[roman807]

In experiments with the segmentation protocol used for MoNuSAC and CoNSeP, BCSS didn't add much value as an additinol segmentation task, because:

• it didn't differentiate well between models (~1% difference in DICE score between best and worst WSI-trained FM)
• the performance was significantly (~30%) below the baseline performance reported at the challenge link.

Find a setup that improves the points mentioned above and add it to the leaderboard.