[ARM] Fix #31581: az deployment group create: Fix error message being hidden when template validation fails (#31965)

Author: micromaomao

src/azure-cli/azure/cli/command_modules/resource/_utils.py

@@ -87,12 +87,7 @@ def _build_preflight_error_message(preflight_error):
 
 
 def _build_http_response_error_message(http_error):
-    from azure.core.exceptions import StreamClosedError, StreamConsumedError
-    try:
-        error_txt = http_error.response.internal_response.text
-        error_info = json.loads(error_txt)['error']
-    except (StreamClosedError, StreamConsumedError):
-        error_info = http_error.response.json()['error']
+    error_info = http_error.response.json()['error']
     error_details = error_info.pop('details') if 'details' in error_info else []
     err_messages = [f'{json.dumps(error_info)}']