Remove trailing underscore in superanimal scorer names

[maximpavliv]

Cleans up the DLC SuperAnimal scorer naming introduced by mistake in PR #3066, where an
extra trailing underscore was appended when a detector was used.

• Trailing underscores are now removed when concatenating detector_snapshot_path or torchvision_detector_name.
• Ensures cleaner and more consistent scorer names.

Example:

• Previously: superanimal_bird_resnet_50_fasterrcnn_mobilenet_v3_large_fpn_
• Now: superanimal_bird_resnet_50_fasterrcnn_mobilenet_v3_large_fpn