[Refactor] Adjustments to moe_comm_method selection process (#3001)

### What this PR does / why we need it?
Fix issues mentioned in
https://github.com/vllm-project/vllm-ascend/pull/2791 and some minor
refactoring.
1. Use Enum instead of string.
2. Avoid setting a new property to forward_context in
AscendFusedMoE.forward().
3. Enabling TokenDispatcherWithMoge.
4. Remove redundant code.

### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?

Qwen3-30B-A3B/Qwen3-30B-A3B-W8A8/DeepSeek-V3-W4A8-Pruing/deepseek-mtp/pangu-pro-moe-pruing:
1. Enable/Disable EP
2. Aclgraph & eager


- vLLM version: v0.10.2
- vLLM main:
9607d5eb44

Signed-off-by: Pr0Wh1teGivee <calvin_zhu0210@outlook.com>
Co-authored-by: weijinqian0 <12153182+weijinqian0@users.noreply.github.com>

vllm_ascend/ops/moe/moe_mlp.py

@@ -21,6 +21,7 @@ import torch_npu
 from torch.nn.functional import pad
 from vllm.forward_context import get_forward_context
 
+from vllm_ascend.ascend_forward_context import MoECommType
 from vllm_ascend.utils import dispose_tensor, is_310p
 
 
@@ -76,7 +77,7 @@ def quant_apply_mlp(hidden_states: torch.Tensor,
     bias1, bias2 = None, None
     _output_dtype = w2_scale.dtype
 
-    is_mc2 = get_forward_context().moe_comm_method_name == "mc2commimpl"
+    is_mc2 = get_forward_context().moe_comm_type == MoECommType.MC2
     if w1_scale_bias is None and is_mc2:
         if w1_scale.dtype != torch.float32:
             w1_scale = w1_scale.to(torch.float32)