tests: rework the actually useful tests to live in the integration crate

crates/irtt-client/Cargo.toml

@@ -42,9 +42,3 @@ doc-scrape-examples = true
 name = "managed_client"
 required-features = ["tokio"]
 doc-scrape-examples = true
-
-[dev-dependencies]
-# Keep the packaged client testable against the latest published server while
-# workspace tests continue to exercise the local source through this path.
-irtt-server = { version = "0.5.1", path = "../irtt-server" }
-tokio = { version = "1.53.1", default-features = false, features = ["rt", "sync"] }