[Bugfix] fix nightly multi-node EPLB tests' "DYNAMIC_EPLB=true" environment not working (#4223)

### What this PR does / why we need it?
fix nightly multi-node EPLB tests by adjusting
vllm_ascend\eplb\core\eplb_utils.py dynamic_eplb gate checking
### Does this PR introduce _any_ user-facing change?
no

- vLLM version: v0.11.0
- vLLM main:
2918c1b49c

---------

Signed-off-by: 白永斌 <baiyongbin3@h-partners.com>
Signed-off-by: 欧派果奶我还要 <47294568+845473182@users.noreply.github.com>
Co-authored-by: 白永斌 <baiyongbin3@h-partners.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

vllm_ascend/patch/platform/__init__.py

@@ -16,11 +16,12 @@
 
 import os
 
+import vllm_ascend.envs as envs_ascend
 import vllm_ascend.patch.platform.patch_config  # noqa
 import vllm_ascend.patch.platform.patch_distributed  # noqa
 import vllm_ascend.patch.platform.patch_mamba_config  # noqa
 import vllm_ascend.patch.platform.patch_sched_yield  # noqa
 
-if os.getenv("DYNAMIC_EPLB", "false") == "true" or os.getenv(
+if envs_ascend.DYNAMIC_EPLB not in ("true", "1") or os.getenv(
         "EXPERT_MAP_RECORD", "false") == "true":
     import vllm_ascend.patch.platform.patch_multiproc_executor  # noqa