Add rust integration tests (ex: with etcd/nats)

[rmccorm4]

See #129 (comment)

Goals:

• Run feature-gated tests that have more requirements (similar to pytest marks) such as etcd/nats servers running in background
• ex: https://github.com/search?q=repo%3Atriton-inference-server%2Ftriton_distributed+integration+test+language%3ARust+&type=code

For the soak test specifically, may have two variants - quick 1minute test as an integration test, and longer stress test nightly? Can start with the quick test and evaluate. Soak test duration is configurable:

triton_distributed/runtime/rust/tests/soak.rs

Line 103 in 31494da

let run_duration = std::env::var("TRD_SOAK_RUN_DURATION").unwrap_or("1m".to_string());

[rmccorm4]

@tmonty12