Remove box (Surma's private container service client) and spikes; drop personal hosts and paths from docs and code

host/tests/builder-fixture/build.rs

@@ -3,7 +3,7 @@ fn main() {
     if std::env::var("SAUSAGE_TEST_NO_BUILDER_SANDBOX").as_deref() == Ok("1") {
         println!("cargo:warning=namespace assertions skipped: builder sandbox disabled");
     } else {
-        assert!(!std::path::Path::new("/home/surma/.ssh").exists());
+        assert!(!std::path::Path::new("/home").exists());
         assert!(
             !std::path::Path::new(&std::env::var("HOME").unwrap())
                 .join(".ssh")