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/core/routers/safety.py

@@ -10,7 +10,7 @@ from llama_stack.apis.inference import (
     Message,
 )
 from llama_stack.apis.safety import RunShieldResponse, Safety
-from llama_stack.apis.safety.safety import ModerationObject, OpenAICategories
+from llama_stack.apis.safety.safety import ModerationObject
 from llama_stack.apis.shields import Shield
 from llama_stack.log import get_logger
 from llama_stack.providers.datatypes import RoutingTable
@@ -82,20 +82,5 @@ class SafetyRouter(Safety):
             input=input,
             model=model,
         )
-        self._validate_required_categories_exist(response)
 
         return response
-
-    def _validate_required_categories_exist(self, response: ModerationObject) -> None:
-        """Validate the ProviderImpl response contains the required Open AI moderations categories."""
-        required_categories = list(map(str, OpenAICategories))
-
-        categories = response.results[0].categories
-        category_applied_input_types = response.results[0].category_applied_input_types
-        category_scores = response.results[0].category_scores
-
-        for i in [categories, category_applied_input_types, category_scores]:
-            if not set(required_categories).issubset(set(i.keys())):
-                raise ValueError(
-                    f"ProviderImpl response is missing required categories: {set(required_categories) - set(i.keys())}"
-                )