### What this PR does / why we need it?
The attention mechanism in the ViT model architecture of Qwen2.5VL
consists of two parts and does not support using cache to pass sequence
lengths.
### Does this PR introduce _any_ user-facing change?
remove seq_lens_cache
### How was this patch tested?
- vLLM version: v0.16.0
- vLLM main:
15d76f74e2
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Signed-off-by: tanhaoan333 <tanhaoan@huawei.com>