[v0.18.0][Bugfix]Fix Error "AttributeError: 'AscendCompressedTensorsConfig' obiect has no attribute 'enabling_fa_quant'" (#7748)

### What this PR does / why we need it?
cherry-pick from https://github.com/vllm-project/vllm-ascend/pull/7736

**Error information**
When the quantized weights in CompressedTensors format of the kimi-k2
model are used, the following error is reported:
`AttributeError: 'AscendCompressedTensorsConfig' obiect has no attribute
'enabling_fa_quant'`

**Error Cause**
Currently, FA3 quantization supports only the weights of modelslim
quantization. The added methods are not defined in
AscendCompressedTensorsConfig.

**Solution**
Before invoking related methods, check whether the FA3 feature is
enabled.
Additionally, the unused `get_scaled_act_names` method and its
corresponding unit test have been removed.

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

### How was this patch tested?
Existing unit tests were updated by removing a deprecated test case, and
the refactored logic was reviewed for correctness.

Signed-off-by: Wang Kunpeng <1289706727@qq.com>

vllm_ascend/quantization/utils.py

@@ -197,3 +197,12 @@ def maybe_auto_detect_quantization(vllm_config) -> None:
     from vllm.config import VllmConfig as _VllmConfig
 
     vllm_config.quant_config = _VllmConfig._get_quantization_config(model_config, vllm_config.load_config)
+
+
+def enable_fa_quant(vllm_config, layer_name=None) -> bool:
+    if vllm_config.quant_config is not None and getattr(vllm_config.quant_config, "enable_fa_quant", False):
+        if layer_name is not None:
+            return vllm_config.quant_config.enabling_fa_quant(vllm_config, layer_name)
+        else:
+            return True
+    return False