fix: apply cache size limit for VisionAttention

[mickqian]

Motivation

enforce an upper-bound limit for VisionAttention mask cache size.

This is included in #3203, and moved to here.

Modifications

Checklist

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[mickqian]

ref #3651

[zhaochenyang20]

@yizhang2077 Will merge it after the CI.

[Lzhang-hub]

@mickqian I use the latest version run qwen2.5-vl-7b model with command

python -m sglang.launch_server --model-path Qwen/Qwen2.5-VL-7B-Instruct --host 0.0.0.0 --port 8080  --chat-template qwen2-vl --chunked-prefill-size -1 --disable-radix-cache --mm-attention-backend fa3 --attention-backend fa3  --enable-torch-compile --cuda-graph-bs 80 --torch-compile-max-bs 80

then benchmark server with concurrency=80, after run sometime, server got OOM error