Fix: Limit the number of generated questions (#13596)

llama-index-core/llama_index/core/llama_dataset/generator.py

...x-core/llama_index/core/llama_dataset/legacy/embedding.py

...ning/llama_index/finetuning/cross_encoders/dataset_gen.py

...ex-finetuning/llama_index/finetuning/embeddings/common.py

llama-index-finetuning/pyproject.toml

...packs-raft-dataset/llama_index/packs/raft_dataset/base.py

...index-packs/llama-index-packs-raft-dataset/pyproject.toml