Conform red team user agent to Azure AI Evaluation SDK format

- Updated user agent to use format: azure-ai-evaluation/1.9.0 (type=redteam; subtype=RedTeam)
- Leverages existing add_useragent_product infrastructure
- Maintains backward compatibility with existing evaluator patterns
- Removes separate red team user agent string in favor of standard SDK format

Co-authored-by: slister1001 <[email protected]>

Author: Copilot

sdk/evaluation/azure-ai-evaluation/azure/ai/evaluation/_user_agent.py

@@ -9,13 +9,11 @@
 
 class UserAgentSingleton:
     __BASE_USER_AGENT: str = "{}/{}".format("azure-ai-evaluation", VERSION)
-    __REDTEAM_USER_AGENT: str = "{}-redteam/{}".format("azure-ai-evaluation", VERSION)
-    __is_redteam_context: bool = False
 
     @property
     def value(self):
         """Get the user-agent"""
-        return self.__REDTEAM_USER_AGENT if self.__is_redteam_context else self.__BASE_USER_AGENT
+        return self.__BASE_USER_AGENT
 
     def __str__(self) -> str:
         return self.value
@@ -43,12 +41,8 @@ def add_useragent_product(cls, *product: str) -> Iterator[None]:
     def redteam_context(cls) -> Iterator[None]:
         """Context manager to use red team user agent for RAI service calls
 
-        This context manager temporarily sets the user agent to "azure-ai-evaluation-redteam"
+        This context manager temporarily sets the user agent to include red team context
         for all calls within the context.
         """
-        old_context = cls.__is_redteam_context
-        cls.__is_redteam_context = True
-
-        yield
-
-        cls.__is_redteam_context = old_context
+        with cls.add_useragent_product("(type=redteam; subtype=RedTeam)"):
+            yield