Main2main upgrade vllm commit to 03 19 17:00 (#7478)

### What this PR does / why we need it?
Upgrade vllm commit to 2026.03.19.

1.Fix socket removed from StatelessProcessGroup. Upstream vLLM PR
[#36330](https://github.com/vllm-project/vllm/pull/36330) ("elastic_ep:
Fix stateless group port races") refactored StatelessProcessGroup and
removed the socket: socket.socket | None field. The socket ownership was
moved to a new create_tcp_store() helper instead of being stored as a
field on the dataclass.

2.fix `virtual_engine` parameter removed from `set_forward_context().
Upstream [V0 Deprecation] Deprecate virtual engine
[#37195](https://github.com/vllm-project/vllm/pull/37195)

### Does this PR introduce _any_ user-facing change?
NA

### How was this patch tested?
NA

- vLLM version: v0.17.0
- vLLM main:
8b6325758c

---------

Signed-off-by: leo-pony <nengjunma@outlook.com>

docs/source/community/versioning_policy.md

@@ -59,7 +59,7 @@ For main branch of vLLM Ascend, we usually make it compatible with the latest vL
 
 | vLLM Ascend | vLLM         | Python           | Stable CANN | PyTorch/torch_npu  |
 |-------------|--------------|------------------|-------------|--------------------|
-|     main    | 8b6325758cce5f9c36d38f2462edbd368b97a07c, v0.18.0 tag | >= 3.10, < 3.12   | 8.5.0 | 2.9.0 / 2.9.0 |
+|     main    | 6a9cceb219fcbd6b1eb540ddfdc77ec160f0e209, v0.18.0 tag | >= 3.10, < 3.12   | 8.5.0 | 2.9.0 / 2.9.0 |
 
 ## Release cadence