The new rpc::optional parameter must come after any existing parameters,
including the rpc::source parameters, otherwise it will break
compatibility.
The regression was introduced in:
```
commit fd3c089ccc
Author: Tomasz Grabiec <tgrabiec@scylladb.com>
Date: Thu Oct 26 00:35:19 2023 +0200
service: range_streamer: Propagate topology_guard to receivers
```
We need to backport this patch ASAP before we release anything that
contains commit fd3c089ccc.
Refs: #16941Fixes: #17175Closesscylladb/scylladb#17176