Remove chunked_prefill_for_mla and fix ring_mla bug (#2781)

### What this PR does / why we need it?
Remove chunked prefill for mla branch in mla , and change dtype of
prefill_mask to avoid accuracy problem
### Does this PR introduce _any_ user-facing change?
NO
### How was this patch tested?

- vLLM version: v0.10.2
- vLLM main:
ef7eefe17a

---------

Signed-off-by: SunnyLee219 <3294305115@qq.com>

docs/source/locale/zh_CN/LC_MESSAGES/user_guide/configuration/additional_config.po

@@ -148,10 +148,6 @@ msgid ""
 " to be passed in."
 msgstr "在为MOE模型使用专家负载均衡时，需要传入专家映射路径。"
 
-#: ../../user_guide/configuration/additional_config.md
-msgid "`chunked_prefill_for_mla`"
-msgstr "`chunked_prefill_for_mla`"
-
 #: ../../user_guide/configuration/additional_config.md
 msgid "`False`"
 msgstr "`False`"

docs/source/user_guide/configuration/additional_config.md

@@ -30,7 +30,6 @@ The following table lists the additional configuration options available in vLLM
 | `ascend_scheduler_config`     | dict | `{}` | The config options for ascend scheduler                                                       |
 | `refresh`                     | bool | `false` | Whether to refresh global ascend config content. This value is usually used by rlhf or ut/e2e test case.     |
 | `expert_map_path`             | str  | `None` | When using expert load balancing for the MOE model, an expert map path needs to be passed in. |
-| `chunked_prefill_for_mla`     | bool | `False` | Whether to enable the fused operator-like chunked_prefill. |
 | `enable_prefetch`     | bool | `False` | Whether to enable weight prefetch. |
 | `kv_cache_dtype`     | str | `None` | When using the kv cache quantization method, kv cache dtype needs to be set, currently only int8 is supported. |
 | `enable_shared_expert_dp`     | bool | `False` | When the shared expert in DP, it has better performance but consumes more memory. Currently only DeepSeek series models are supported to use. |