Testodrome measures uptime based on the failed requests and errors. In
case of testodrome request we send back error based on the service. This
will help us distinguish error types in testodrome and rely on the
uptime SLI.
This upgrades the `proxy/` crate as well as the forked libraries in
`libs/proxy/` to edition 2024.
Also reformats the imports of those forked libraries via:
```
cargo +nightly fmt -p proxy -p postgres-protocol2 -p postgres-types2 -p tokio-postgres2 -- -l --config imports_granularity=Module,group_imports=StdExternalCrate,reorder_imports=true
```
It can be read commit-by-commit: the first commit has no formatting
changes, only changes to accomodate the new edition.
Part of #10918