fix: exclude observations if too few samples in bin

[sarakolding]

• [x] I have battle-tested on Overtaci (RMAPPS1279)
• [x] At least one of the commits is prefixed with either "fix:" or "feat:"

[MartinBernstorff]

Hey Sara! Just wanna say that this'll be super helpful - I'm trying to run some plots now where this defect is causing them to be empty.

[github-actions[bot]]

Coverage Report •

File	Stmts	Miss	Cover	Missing
src/psycop_model_training/model_eval/base_artifacts/plots
utils.py	30	2	93%	22, 62
src/psycop_model_training/utils
utils.py	95	22	77%	45, 148–158, 216, 274–275, 292, 296, 326–329, 337–341, 346–357, 369–373
TOTAL	1980	453	77%

Tests	Skipped	Failures	Errors	Time
49	1 :zzz:	0 :x:	0 :fire:	1m 55s :stopwatch:

[MartinBernstorff]

Det ser super ud! Jeg skriver lige en test eller to, og så er den vist klar til merge.