[P/D][main]Offline the llmdatadist connector related parts of the code and files. (#4780)

### What this PR does / why we need it?
As support for the mooncake connector is now available, the llmdatadist
connector is no longer being maintained, so the llmdatadist-related
files need to be retired.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
By ci

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

---------

Signed-off-by: wangxiaoteng <wangxiaoteng@huawei.com>
Signed-off-by: liziyu <liziyu16@huawei.com>
Co-authored-by: liziyu <liziyu16@huawei.com>

.github/workflows/vllm_ascend_test_pr_light.yaml

@@ -139,7 +139,6 @@ jobs:
             --ignore tests/ut/model_loader/netloader/test_netloader_elastic.py \
             --ignore tests/ut/kv_connector/test_remote_prefill_lifecycle.py \
             --ignore tests/ut/kv_connector/test_remote_decode_lifecycle.py \
-            --ignore tests/ut/kv_connector/test_llmdatadist_connector.py \
             --ignore tests/ut/core/test_scheduler_dynamic_batch.py
 
       - name: Upload coverage to Codecov