The `test` attribute doesn't really matter to rust-analyzer, so we can
make use of its cfg to have it think its just the standard test
attribute which should make rust-analyzer slightly less resource
intensive in zed. It also should prevent some IDE features from possibly
failing within tests.

Notably this has no effect outside of this repo, as the `rust-analyzer`
cfg only takes effect on workspace member crates.

Ideally we'd use the ignored proc macro config here but rust-analyzer
still doesn't have toml configs working unfortunately.

Release Notes:

- N/A