EMR 7.8.0 livy http api not working

I've got a new emr cluster (version 7.8.0) with spark set up. Spark version is 3.5.4 and livy is 0.8.0. Spark is working correctly. However, I seem to be having issues with livy.

I've ssh-ed to the emr cluster. I've checked that the livy-server service is active (running). When I run:

```
curl http://127.0.0.1:8998/sessions
```

the response is:

```
curl: (1) Received HTTP/0.9 when not allowed
```

I'd appreciate any help in understanding the issue and pointers on resolving this.

Start by reproducing the reported curl request against Livy on an EMR 7.8.0 cluster with Spark 3.5.4 and Livy 0.8.0, confirming that livy-server is running. Investigate why the /sessions endpoint returns HTTP/0.9, and consider the issue resolved when the cause and a working request or configuration are documented.

Written by the indexing model from the issue text.