feat: (re-)enable Databricks inference adapter (#3500)

# What does this PR do?

add/enable the Databricks inference adapter

Databricks inference adapter was broken, closes #3486 

- remove deprecated completion / chat_completion endpoints
- enable dynamic model listing w/o refresh, listing is not async
- use SecretStr instead of str for token
- backward incompatible change: for consistency with databricks docs,
env DATABRICKS_URL -> DATABRICKS_HOST and DATABRICKS_API_TOKEN ->
DATABRICKS_TOKEN
- databricks urls are custom per user/org, add special recorder handling
for databricks urls
- add integration test --setup databricks
- enable chat completions tests
- enable embeddings tests
- disable n > 1 tests
- disable embeddings base64 tests
- disable embeddings dimensions tests

note: reasoning models, e.g. gpt oss, fail because databricks has a
custom, incompatible response format

## Test Plan

ci and 

```
./scripts/integration-tests.sh --stack-config server:ci-tests --setup databricks --subdirs inference --pattern openai
```

note: databricks needs to be manually added to the ci-tests distro for
replay testing

tests/integration/recordings/responses/7f53b458dad9.json

@@ -0,0 +1,83 @@
+{
+  "request": {
+    "method": "POST",
+    "url": "__databricks__/serving-endpoints/v1/chat/completions",
+    "headers": {},
+    "body": {
+      "model": "databricks-meta-llama-3-3-70b-instruct",
+      "messages": [
+        {
+          "role": "user",
+          "content": "What's the weather in Tokyo? Use the get_weather function to get the weather."
+        }
+      ],
+      "stream": false,
+      "tools": [
+        {
+          "type": "function",
+          "function": {
+            "name": "get_weather",
+            "description": "Get the weather in a given city",
+            "parameters": {
+              "type": "object",
+              "properties": {
+                "city": {
+                  "type": "string",
+                  "description": "The city to get the weather for"
+                }
+              }
+            }
+          }
+        }
+      ]
+    },
+    "endpoint": "/v1/chat/completions",
+    "model": "databricks-meta-llama-3-3-70b-instruct"
+  },
+  "response": {
+    "body": {
+      "__type__": "openai.types.chat.chat_completion.ChatCompletion",
+      "__data__": {
+        "id": "chatcmpl_e54eaa97-ace3-4af6-b3a2-b1627bc77488",
+        "choices": [
+          {
+            "finish_reason": "tool_calls",
+            "index": 0,
+            "logprobs": null,
+            "message": {
+              "content": null,
+              "refusal": null,
+              "role": "assistant",
+              "annotations": null,
+              "audio": null,
+              "function_call": null,
+              "tool_calls": [
+                {
+                  "id": "call_9c7f9e5f-c6eb-4c3c-a7b3-e9fe0e786b50",
+                  "function": {
+                    "arguments": "{ \"city\": \"Tokyo\" }",
+                    "name": "get_weather"
+                  },
+                  "type": "function"
+                }
+              ]
+            }
+          }
+        ],
+        "created": 1758326507,
+        "model": "meta-llama-3.3-70b-instruct-121024",
+        "object": "chat.completion",
+        "service_tier": null,
+        "system_fingerprint": null,
+        "usage": {
+          "completion_tokens": 15,
+          "prompt_tokens": 682,
+          "total_tokens": 697,
+          "completion_tokens_details": null,
+          "prompt_tokens_details": null
+        }
+      }
+    },
+    "is_streaming": false
+  }
+}