chore: Change moderations api response to Provider returned categories (#3098)

# What does this PR do?
To be compliant with model policies for LLAMA, just return the
categories as is from provider, we will lose the OAI compat in
moderations api response.

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->

## Test Plan
`SAFETY_MODEL=llama-guard3:8b LLAMA_STACK_CONFIG=starter uv run pytest
-v tests/integration/safety/test_safety.py
--text-model=llama3.2:3b-instruct-fp16
--embedding-model=all-MiniLM-L6-v2 --safety-shield=ollama`

llama_stack/apis/safety/safety.py

@@ -4,7 +4,7 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
-from enum import Enum, StrEnum
+from enum import Enum
 from typing import Any, Protocol, runtime_checkable
 
 from pydantic import BaseModel, Field
@@ -15,27 +15,6 @@ from llama_stack.providers.utils.telemetry.trace_protocol import trace_protocol
 from llama_stack.schema_utils import json_schema_type, webmethod
 
 
-# OpenAI Categories to return in the response
-class OpenAICategories(StrEnum):
-    """
-    Required set of categories in moderations api response
-    """
-
-    VIOLENCE = "violence"
-    VIOLENCE_GRAPHIC = "violence/graphic"
-    HARRASMENT = "harassment"
-    HARRASMENT_THREATENING = "harassment/threatening"
-    HATE = "hate"
-    HATE_THREATENING = "hate/threatening"
-    ILLICIT = "illicit"
-    ILLICIT_VIOLENT = "illicit/violent"
-    SEXUAL = "sexual"
-    SEXUAL_MINORS = "sexual/minors"
-    SELF_HARM = "self-harm"
-    SELF_HARM_INTENT = "self-harm/intent"
-    SELF_HARM_INSTRUCTIONS = "self-harm/instructions"
-
-
 @json_schema_type
 class ModerationObjectResults(BaseModel):
     """A moderation object.
@@ -43,20 +22,6 @@ class ModerationObjectResults(BaseModel):
     :param categories: A list of the categories, and whether they are flagged or not.
     :param category_applied_input_types: A list of the categories along with the input type(s) that the score applies to.
     :param category_scores: A list of the categories along with their scores as predicted by model.
-    Required set of categories that need to be in response
-    - violence
-    - violence/graphic
-    - harassment
-    - harassment/threatening
-    - hate
-    - hate/threatening
-    - illicit
-    - illicit/violent
-    - sexual
-    - sexual/minors
-    - self-harm
-    - self-harm/intent
-    - self-harm/instructions
     """
 
     flagged: bool