LLMService: cancel function calls on interruptions by default

CHANGELOG.md

@@ -60,6 +60,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Function calls are now cancelled by default if there's an interruption. To
+  disable this behavior you can set `cancel_on_interruption=False` when
+  registering the function call. Since function calls are executed as tasks you
+  can tell if a function call has been cancelled by catching the
+  `asyncio.CancelledError` exception (and don't forget to raise it again!).
+
 - Updated OpenTelemetry tracing attribute `metrics.ttfb_ms` to `metrics.ttfb`.
   The attribute reports TTFB in seconds.