feat: (re-)enable Databricks inference adapter

Databricks inference adapter was broken, would not start, see #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 with: ./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

docs/source/providers/inference/remote_databricks.md

@@ -9,13 +9,13 @@ Databricks inference provider for running models on Databricks' unified analytic
 | Field | Type | Required | Default | Description |
 |-------|------|----------|---------|-------------|
 | `url` | `<class 'str'>` | No |  | The URL for the Databricks model serving endpoint |
-| `api_token` | `<class 'str'>` | No |  | The Databricks API token |
+| `api_token` | `<class 'pydantic.types.SecretStr'>` | No |  | The Databricks API token |
 
 ## Sample Configuration
 
 ```yaml
-url: ${env.DATABRICKS_URL:=}
-api_token: ${env.DATABRICKS_API_TOKEN:=}
+url: ${env.DATABRICKS_HOST:=}
+api_token: ${env.DATABRICKS_TOKEN:=}
 
 ```