GBNF grammar tweak for faster Qwen3.6 35B-A3B and Qwen3.6 27B

This content details an optimization of the GBNF grammar for Qwen3.6 35B-A3B and 27B models, resulting in enhanced performance for coding and puzzle-solving. Benchmarking on an RTX 5090 setup with llama.cpp showed a significant uplift, particularly for the 35B-A3B model.