chore: remove /v1/inference/completion and implementations (#3622)

# What does this PR do?

the /inference/completion route is gone. this removes the
implementations.

## Test Plan

ci

llama_stack/providers/remote/inference/bedrock/bedrock.py

@@ -6,12 +6,10 @@
 
 import json
 from collections.abc import AsyncGenerator, AsyncIterator
+from typing import Any
 
 from botocore.client import BaseClient
 
-from llama_stack.apis.common.content_types import (
-    InterleavedContent,
-)
 from llama_stack.apis.inference import (
     ChatCompletionRequest,
     ChatCompletionResponse,
@@ -27,6 +25,7 @@ from llama_stack.apis.inference import (
     ToolDefinition,
     ToolPromptFormat,
 )
+from llama_stack.apis.inference.inference import OpenAICompletion
 from llama_stack.providers.remote.inference.bedrock.config import BedrockConfig
 from llama_stack.providers.utils.bedrock.client import create_bedrock_client
 from llama_stack.providers.utils.inference.model_registry import (
@@ -36,7 +35,6 @@ from llama_stack.providers.utils.inference.openai_compat import (
     OpenAIChatCompletionToLlamaStackMixin,
     OpenAICompatCompletionChoice,
     OpenAICompatCompletionResponse,
-    OpenAICompletionToLlamaStackMixin,
     get_sampling_strategy_options,
     process_chat_completion_response,
     process_chat_completion_stream_response,
@@ -89,7 +87,6 @@ class BedrockInferenceAdapter(
     ModelRegistryHelper,
     Inference,
     OpenAIChatCompletionToLlamaStackMixin,
-    OpenAICompletionToLlamaStackMixin,
 ):
     def __init__(self, config: BedrockConfig) -> None:
         ModelRegistryHelper.__init__(self, model_entries=MODEL_ENTRIES)
@@ -109,17 +106,6 @@ class BedrockInferenceAdapter(
         if self._client is not None:
             self._client.close()
 
-    async def completion(
-        self,
-        model_id: str,
-        content: InterleavedContent,
-        sampling_params: SamplingParams | None = None,
-        response_format: ResponseFormat | None = None,
-        stream: bool | None = False,
-        logprobs: LogProbConfig | None = None,
-    ) -> AsyncGenerator:
-        raise NotImplementedError()
-
     async def chat_completion(
         self,
         model_id: str,
@@ -221,3 +207,31 @@ class BedrockInferenceAdapter(
         user: str | None = None,
     ) -> OpenAIEmbeddingsResponse:
         raise NotImplementedError()
+
+    async def openai_completion(
+        self,
+        # Standard OpenAI completion parameters
+        model: str,
+        prompt: str | list[str] | list[int] | list[list[int]],
+        best_of: int | None = None,
+        echo: bool | None = None,
+        frequency_penalty: float | None = None,
+        logit_bias: dict[str, float] | None = None,
+        logprobs: bool | None = None,
+        max_tokens: int | None = None,
+        n: int | None = None,
+        presence_penalty: float | None = None,
+        seed: int | None = None,
+        stop: str | list[str] | None = None,
+        stream: bool | None = None,
+        stream_options: dict[str, Any] | None = None,
+        temperature: float | None = None,
+        top_p: float | None = None,
+        user: str | None = None,
+        # vLLM-specific parameters
+        guided_choice: list[str] | None = None,
+        prompt_logprobs: int | None = None,
+        # for fill-in-the-middle type completion
+        suffix: str | None = None,
+    ) -> OpenAICompletion:
+        raise NotImplementedError("OpenAI completion not supported by the Bedrock provider")