[1/N][Refactor][Quantization] remove redundant quantizer class (#2680)

### What this PR does / why we need it?

AscendQuantizer/LLMQuantizer class is used to select quant method based
on quant config and some other arguments,
but it is more simple and clean replacing these classes with map. So i
remove them.

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

### How was this patch tested?

ut and e2e test


- vLLM version: v0.10.1.1
- vLLM main:
6997a25ac6

Signed-off-by: 22dimensions <waitingwind@foxmail.com>

vllm_ascend/torchair/quantization/torchair_quantizer.py

@@ -1,29 +0,0 @@
-from vllm_ascend.quantization.quantizer import VLLMAscendQuantizer
-from vllm_ascend.torchair.quantization.torchair_w4a8_dynamic import (
-    TorchairAscendW4A8DynamicFusedMoEMethod,
-    TorchairAscendW4A8DynamicLinearMethod)
-from vllm_ascend.torchair.quantization.torchair_w8a8_dynamic import (
-    TorchairAscendW8A8DynamicFusedMoEMethod,
-    TorchairAscendW8A8DynamicLinearMethod)
-
-
-class TorchairW8A8DYNAMICQuantizer(VLLMAscendQuantizer):
-
-    @staticmethod
-    def build_linear_method():
-        return TorchairAscendW8A8DynamicLinearMethod()
-
-    @staticmethod
-    def build_moe_method():
-        return TorchairAscendW8A8DynamicFusedMoEMethod()
-
-
-class TorchairW4A8DYNAMICQuantizer(VLLMAscendQuantizer):
-
-    @staticmethod
-    def build_linear_method():
-        return TorchairAscendW4A8DynamicLinearMethod()
-
-    @staticmethod
-    def build_moe_method():
-        return TorchairAscendW4A8DynamicFusedMoEMethod()