chore: update the ollama inference impl to use OpenAIMixin for openai-compat functions (#3395)

# What does this PR do?

update Ollama inference provider to use OpenAIMixin for openai-compat
endpoints

## Test Plan

ci

tests/integration/recordings/responses/6412295819a1.json

@@ -0,0 +1,43 @@
+{
+  "request": {
+    "method": "POST",
+    "url": "http://0.0.0.0:11434/v1/v1/completions",
+    "headers": {},
+    "body": {
+      "model": "llama3.2:3b-instruct-fp16",
+      "prompt": "Respond to this question and explain your answer. Complete the sentence using one word: Roses are red, violets are ",
+      "stream": false,
+      "extra_body": {}
+    },
+    "endpoint": "/v1/completions",
+    "model": "llama3.2:3b-instruct-fp16"
+  },
+  "response": {
+    "body": {
+      "__type__": "openai.types.completion.Completion",
+      "__data__": {
+        "id": "cmpl-104",
+        "choices": [
+          {
+            "finish_reason": "stop",
+            "index": 0,
+            "logprobs": null,
+            "text": "blue.\n\nI completed the sentence with \"blue\" because it is a common completion used to complete the traditional nursery rhyme, which ends with:\n\nRoses are red,\nViolets are blue.\n\nThe complete rhyme is often remembered and recited as follows:\n\nRoses are red,\nViolets are blue,\nSugar is sweet,\nAnd so are you!"
+          }
+        ],
+        "created": 1757857132,
+        "model": "llama3.2:3b-instruct-fp16",
+        "object": "text_completion",
+        "system_fingerprint": "fp_ollama",
+        "usage": {
+          "completion_tokens": 72,
+          "prompt_tokens": 50,
+          "total_tokens": 122,
+          "completion_tokens_details": null,
+          "prompt_tokens_details": null
+        }
+      }
+    },
+    "is_streaming": false
+  }
+}