tests: fast host suites

The timing rules are in two tests (upgrade_and_discovery_deadlines,
stop_deadlines). All other tests use a grace period of 0 or core.stop,
poll with deadlines instead of sleeping, and use the persistent cache in
CARGO_TARGET_TMPDIR. The 128-cycle singleton test is an ignored stress
test that nix flake check runs; the normal run has a 4-cycle sample.
Warm, the activation suite takes 12 s (was 47 s), and cargo test
--workspace takes 65 s.

cli/tests/console.rs

@@ -14,7 +14,7 @@ fn fixture() -> PathBuf {
             .parent()
             .unwrap()
             .to_owned();
-        let target = root.join("target/core/console-guests");
+        let target = PathBuf::from(concat!(env!("CARGO_TARGET_TMPDIR"), "/guests"));
         let status = std::process::Command::new("cargo")
             .args([
                 "build",
@@ -51,10 +51,7 @@ impl TestWorld {
         Self(root)
     }
     async fn start(&self) -> Host {
-        let cache = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
-            .parent()
-            .unwrap()
-            .join("target/core/console-cache");
+        let cache = PathBuf::from(concat!(env!("CARGO_TARGET_TMPDIR"), "/cache"));
         Host::start_with_cache(&self.0, &cache).await.unwrap()
     }
 }